From 1b2dc3638f90508dbc98dcd8a518153fb0db62d0 Mon Sep 17 00:00:00 2001 From: Juergen Hoeller Date: Mon, 30 Jan 2017 22:15:53 +0100 Subject: [PATCH] Revisit Assert to avoid single-arg assert methods (with refined messages) Issue: SPR-15196 --- .../aop/aspectj/TypePatternClassFilter.java | 22 +- .../AbstractAdvisorAutoProxyCreator.java | 5 +- .../AutowiredAnnotationBeanPostProcessor.java | 4 +- .../factory/config/CustomScopeConfigurer.java | 6 +- .../factory/support/AbstractBeanFactory.java | 4 +- .../DefaultCacheInvocationContext.java | 21 +- .../interceptor/JCacheAspectSupport.java | 16 +- .../quartz/SchedulerFactoryBean.java | 5 +- .../CacheResolverAdapterTests.java | 17 +- .../cache/interceptor/CacheOperation.java | 18 +- .../ComponentScanAnnotationParser.java | 6 +- .../support/DefaultLifecycleProcessor.java | 8 +- .../standard/DateTimeFormatterFactory.java | 4 +- .../weblogic/WebLogicClassLoaderAdapter.java | 17 +- .../ClassWithComplexConstructor.java | 7 +- .../ConfigurationClassPostProcessorTests.java | 8 +- .../context/support/Service.java | 5 +- .../standard/DateTimeFormattingTests.java | 3 +- .../SpringValidatorAdapterTests.java | 2 +- .../org/springframework/core/Constants.java | 2 +- .../core/ParameterizedTypeReference.java | 6 +- .../core/SerializableTypeWrapper.java | 7 +- .../env/JOptCommandLinePropertySource.java | 13 +- .../java/org/springframework/util/Assert.java | 209 ++++-------------- .../util/ConcurrentReferenceHashMap.java | 4 +- .../org/springframework/util/AssertTests.java | 129 ++++++----- .../expression/spel/ast/OpDec.java | 4 +- .../expression/spel/ast/OpInc.java | 4 +- .../expression/spel/ast/OpPlus.java | 4 +- .../expression/spel/ast/Operator.java | 4 +- .../InternalSpelExpressionParser.java | 28 +-- .../expression/spel/standard/Tokenizer.java | 9 +- .../jdbc/core/ParameterDisposer.java | 16 +- ...dlerMethodReturnValueHandlerComposite.java | 11 +- .../messaging/simp/SimpMessagingTemplate.java | 14 +- .../SimpAnnotationMethodMessageHandler.java | 4 +- .../broker/SimpleBrokerMessageHandler.java | 7 +- .../AbstractMessageBrokerConfiguration.java | 6 +- .../simp/config/MessageBrokerRegistry.java | 6 +- .../simp/stomp/DefaultStompSession.java | 4 +- .../simp/stomp/StompClientSupport.java | 4 +- ...AbstractMonoToListenableFutureAdapter.java | 11 +- .../ReactorNettyTcpStompClientTests.java | 5 +- ...erRelayMessageHandlerIntegrationTests.java | 7 +- .../orm/hibernate5/SessionFactoryUtils.java | 4 +- .../jpa/AbstractEntityManagerFactoryBean.java | 5 +- .../jpa/support/SharedEntityManagerBean.java | 3 +- .../orm/jpa/vendor/HibernateJpaDialect.java | 4 +- .../oxm/xstream/XStreamMarshaller.java | 19 +- .../mock/web/MockAsyncContext.java | 6 +- .../mock/web/MockPageContext.java | 6 +- .../SimpleRequestExpectationManager.java | 4 +- .../standalone/FrameworkExtensionTests.java | 18 +- .../support/ResourceAdapterFactoryBean.java | 8 +- .../UrlBasedViewResolverRegistration.java | 5 +- .../reactive/config/ViewResolverRegistry.java | 10 +- .../handler/AbstractHandlerMapping.java | 23 +- .../handler/AbstractUrlHandlerMapping.java | 15 +- .../method/AbstractHandlerMethodMapping.java | 15 +- .../method/SyncInvocableHandlerMethod.java | 4 +- .../ResponseEntityResultHandler.java | 6 +- .../view/script/ScriptTemplateView.java | 4 +- .../socket/adapter/JettyWebSocketSession.java | 11 +- .../upgrade/JettyRequestUpgradeStrategy.java | 8 +- .../upgrade/TomcatRequestUpgradeStrategy.java | 22 +- .../UndertowRequestUpgradeStrategy.java | 15 +- .../reactive/FlushingIntegrationTests.java | 10 +- .../web/reactive/result/ResolvableMethod.java | 29 ++- ...lAttributeMethodArgumentResolverTests.java | 20 +- .../http/ContentDisposition.java | 5 +- .../springframework/http/ResponseCookie.java | 23 +- .../SimpleClientHttpRequestFactory.java | 6 +- .../reactive/AbstractClientHttpRequest.java | 10 +- ...ppingJackson2CborHttpMessageConverter.java | 9 +- ...pingJackson2SmileHttpMessageConverter.java | 9 +- ...appingJackson2XmlHttpMessageConverter.java | 9 +- .../http/server/ServletServerHttpRequest.java | 6 +- .../AbstractListenerReadPublisher.java | 9 +- .../AbstractListenerWriteFlushProcessor.java | 24 +- .../AbstractListenerWriteProcessor.java | 24 +- .../reactive/AbstractServerHttpResponse.java | 4 +- .../reactive/HttpHandlerAdapterSupport.java | 18 +- .../reactive/ServletHttpHandlerAdapter.java | 39 ++-- .../reactive/ServletServerHttpResponse.java | 11 +- .../reactive/UndertowServerHttpResponse.java | 15 +- .../server/reactive/WriteResultPublisher.java | 13 +- ...thExtensionContentNegotiationStrategy.java | 8 +- ...sfiedServletRequestParameterException.java | 4 +- .../web/context/ContextLoader.java | 6 +- .../web/util/HierarchicalUriComponents.java | 2 +- .../HttpHandlerAdapterSupportTests.java | 16 +- .../bootstrap/AbstractHttpServer.java | 16 +- .../server/reactive/bootstrap/HttpServer.java | 3 +- .../reactive/bootstrap/TomcatHttpServer.java | 4 +- .../mock/web/test/MockAsyncContext.java | 10 +- .../mock/web/test/MockPageContext.java | 6 +- .../util/DefaultUriTemplateHandlerTests.java | 6 +- .../web/servlet/HttpServletBean.java | 4 +- .../handler/AbstractHandlerMethodMapping.java | 8 +- .../handler/AbstractUrlHandlerMapping.java | 28 ++- ...eferredResultMethodReturnValueHandler.java | 13 +- .../HttpHeadersReturnValueHandler.java | 4 +- .../annotation/MvcUriComponentsBuilder.java | 17 +- .../RequestMappingHandlerAdapter.java | 4 +- ...ResponseBodyEmitterReturnValueHandler.java | 9 +- ...reamingResponseBodyReturnValueHandler.java | 4 +- .../support/ServletUriComponentsBuilder.java | 11 +- .../view/ContentNegotiatingViewResolver.java | 4 +- .../view/script/ScriptTemplateView.java | 4 +- .../annotation/ResponseBodyEmitterTests.java | 16 +- .../AbstractWebSocketHandlerRegistration.java | 20 +- .../messaging/DefaultSimpUserRegistry.java | 65 +++--- .../jetty/JettyRequestUpgradeStrategy.java | 6 +- .../AbstractStandardUpgradeStrategy.java | 10 +- .../client/RestTemplateXhrTransport.java | 4 +- .../sockjs/client/WebSocketTransport.java | 12 +- .../session/AbstractSockJsSession.java | 4 +- .../session/StreamingSockJsSession.java | 4 +- 118 files changed, 708 insertions(+), 828 deletions(-) diff --git a/spring-aop/src/main/java/org/springframework/aop/aspectj/TypePatternClassFilter.java b/spring-aop/src/main/java/org/springframework/aop/aspectj/TypePatternClassFilter.java index 9d2bc141c6f..d075741490f 100644 --- a/spring-aop/src/main/java/org/springframework/aop/aspectj/TypePatternClassFilter.java +++ b/spring-aop/src/main/java/org/springframework/aop/aspectj/TypePatternClassFilter.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2012 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -27,6 +27,7 @@ import org.springframework.util.StringUtils; * Spring AOP {@link ClassFilter} implementation using AspectJ type matching. * * @author Rod Johnson + * @author Juergen Hoeller * @since 2.0 */ public class TypePatternClassFilter implements ClassFilter { @@ -76,17 +77,21 @@ public class TypePatternClassFilter implements ClassFilter { * or is recognized as invalid */ public void setTypePattern(String typePattern) { - Assert.notNull(typePattern); + Assert.notNull(typePattern, "Type pattern must not be null"); this.typePattern = typePattern; this.aspectJTypePatternMatcher = PointcutParser.getPointcutParserSupportingAllPrimitivesAndUsingContextClassloaderForResolution(). parseTypePattern(replaceBooleanOperators(typePattern)); } + /** + * Return the AspectJ type pattern to match. + */ public String getTypePattern() { - return typePattern; + return this.typePattern; } + /** * Should the pointcut apply to the given interface or target class? * @param clazz candidate target class @@ -95,9 +100,7 @@ public class TypePatternClassFilter implements ClassFilter { */ @Override public boolean matches(Class clazz) { - if (this.aspectJTypePatternMatcher == null) { - throw new IllegalStateException("No 'typePattern' has been set via ctor/setter."); - } + Assert.state(this.aspectJTypePatternMatcher != null, "No type pattern has been set"); return this.aspectJTypePatternMatcher.matches(clazz); } @@ -108,9 +111,8 @@ public class TypePatternClassFilter implements ClassFilter { *

This method converts back to {@code &&} for the AspectJ pointcut parser. */ private String replaceBooleanOperators(String pcExpr) { - pcExpr = StringUtils.replace(pcExpr," and "," && "); - pcExpr = StringUtils.replace(pcExpr, " or ", " || "); - pcExpr = StringUtils.replace(pcExpr, " not ", " ! "); - return pcExpr; + String result = StringUtils.replace(pcExpr," and "," && "); + result = StringUtils.replace(result, " or ", " || "); + return StringUtils.replace(result, " not ", " ! "); } } diff --git a/spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java b/spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java index 92fc174bea6..d7a8d1168b7 100644 --- a/spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java +++ b/spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2015 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -54,7 +54,8 @@ public abstract class AbstractAdvisorAutoProxyCreator extends AbstractAutoProxyC public void setBeanFactory(BeanFactory beanFactory) { super.setBeanFactory(beanFactory); if (!(beanFactory instanceof ConfigurableListableBeanFactory)) { - throw new IllegalStateException("Cannot use AdvisorAutoProxyCreator without a ConfigurableListableBeanFactory"); + throw new IllegalArgumentException( + "AdvisorAutoProxyCreator requires a ConfigurableListableBeanFactory: " + beanFactory); } initBeanFactory((ConfigurableListableBeanFactory) beanFactory); } diff --git a/spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java b/spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java index daf57d11aaf..de10ab87264 100644 --- a/spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java +++ b/spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -219,7 +219,7 @@ public class AutowiredAnnotationBeanPostProcessor extends InstantiationAwareBean public void setBeanFactory(BeanFactory beanFactory) { if (!(beanFactory instanceof ConfigurableListableBeanFactory)) { throw new IllegalArgumentException( - "AutowiredAnnotationBeanPostProcessor requires a ConfigurableListableBeanFactory"); + "AutowiredAnnotationBeanPostProcessor requires a ConfigurableListableBeanFactory: " + beanFactory); } this.beanFactory = (ConfigurableListableBeanFactory) beanFactory; } diff --git a/spring-beans/src/main/java/org/springframework/beans/factory/config/CustomScopeConfigurer.java b/spring-beans/src/main/java/org/springframework/beans/factory/config/CustomScopeConfigurer.java index aab69b17506..02141ce0985 100644 --- a/spring-beans/src/main/java/org/springframework/beans/factory/config/CustomScopeConfigurer.java +++ b/spring-beans/src/main/java/org/springframework/beans/factory/config/CustomScopeConfigurer.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -102,12 +102,12 @@ public class CustomScopeConfigurer implements BeanFactoryPostProcessor, BeanClas } else if (value instanceof Class) { Class scopeClass = (Class) value; - Assert.isAssignable(Scope.class, scopeClass); + Assert.isAssignable(Scope.class, scopeClass, "Invalid scope class"); beanFactory.registerScope(scopeKey, (Scope) BeanUtils.instantiateClass(scopeClass)); } else if (value instanceof String) { Class scopeClass = ClassUtils.resolveClassName((String) value, this.beanClassLoader); - Assert.isAssignable(Scope.class, scopeClass); + Assert.isAssignable(Scope.class, scopeClass, "Invalid scope class"); beanFactory.registerScope(scopeKey, (Scope) BeanUtils.instantiateClass(scopeClass)); } else { diff --git a/spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java b/spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java index 94839bdb3f7..3e320f8515a 100644 --- a/spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java +++ b/spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -762,7 +762,7 @@ public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport imp @Override public void registerCustomEditor(Class requiredType, Class propertyEditorClass) { Assert.notNull(requiredType, "Required type must not be null"); - Assert.isAssignable(PropertyEditor.class, propertyEditorClass); + Assert.notNull(propertyEditorClass, "PropertyEditor class must not be null"); this.customEditors.put(requiredType, propertyEditorClass); } diff --git a/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultCacheInvocationContext.java b/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultCacheInvocationContext.java index 64d4d2c2ee2..a54429203ba 100644 --- a/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultCacheInvocationContext.java +++ b/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultCacheInvocationContext.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2014 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -44,14 +44,15 @@ class DefaultCacheInvocationContext private final CacheInvocationParameter[] allParameters; - public DefaultCacheInvocationContext(JCacheOperation operation, - Object target, Object[] args) { + + public DefaultCacheInvocationContext(JCacheOperation operation, Object target, Object[] args) { this.operation = operation; this.target = target; this.args = args; this.allParameters = operation.getAllParameters(args); } + @Override public JCacheOperation getOperation() { return this.operation; @@ -94,17 +95,19 @@ class DefaultCacheInvocationContext @Override public T unwrap(Class cls) { - throw new IllegalArgumentException("Could not unwrap to '" + cls.getName() + "'"); + throw new IllegalArgumentException("Cannot unwrap to " + cls); } + @Override public String toString() { - final StringBuilder sb = new StringBuilder("CacheInvocationContext{"); - sb.append("operation=").append(operation); - sb.append(", target=").append(target); - sb.append(", args=").append(Arrays.toString(args)); - sb.append(", allParameters=").append(Arrays.toString(allParameters)); + StringBuilder sb = new StringBuilder("CacheInvocationContext{"); + sb.append("operation=").append(this.operation); + sb.append(", target=").append(this.target); + sb.append(", args=").append(Arrays.toString(this.args)); + sb.append(", allParameters=").append(Arrays.toString(this.allParameters)); sb.append('}'); return sb.toString(); } + } diff --git a/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/JCacheAspectSupport.java b/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/JCacheAspectSupport.java index 8ea51aaebc2..14ee5d53630 100644 --- a/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/JCacheAspectSupport.java +++ b/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/JCacheAspectSupport.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -66,7 +66,7 @@ public class JCacheAspectSupport extends AbstractCacheInvoker implements Initial public void setCacheOperationSource(JCacheOperationSource cacheOperationSource) { - Assert.notNull(cacheOperationSource); + Assert.notNull(cacheOperationSource, "JCacheOperationSource must not be null"); this.cacheOperationSource = cacheOperationSource; } @@ -80,7 +80,7 @@ public class JCacheAspectSupport extends AbstractCacheInvoker implements Initial public void afterPropertiesSet() { Assert.state(getCacheOperationSource() != null, "The 'cacheOperationSource' property is required: " + "If there are no cacheable methods, then don't use a cache aspect."); - Assert.state(getErrorHandler() != null, "The 'errorHandler' is required"); + Assert.state(getErrorHandler() != null, "The 'errorHandler' property is required"); this.cacheResultInterceptor = new CacheResultInterceptor(getErrorHandler()); this.cachePutInterceptor = new CachePutInterceptor(getErrorHandler()); @@ -128,23 +128,23 @@ public class JCacheAspectSupport extends AbstractCacheInvoker implements Initial BasicOperation operation = context.getOperation(); if (operation instanceof CacheResultOperation) { - return cacheResultInterceptor.invoke( + return this.cacheResultInterceptor.invoke( (CacheOperationInvocationContext) context, adapter); } else if (operation instanceof CachePutOperation) { - return cachePutInterceptor.invoke( + return this.cachePutInterceptor.invoke( (CacheOperationInvocationContext) context, adapter); } else if (operation instanceof CacheRemoveOperation) { - return cacheRemoveEntryInterceptor.invoke( + return this.cacheRemoveEntryInterceptor.invoke( (CacheOperationInvocationContext) context, adapter); } else if (operation instanceof CacheRemoveAllOperation) { - return cacheRemoveAllInterceptor.invoke( + return this.cacheRemoveAllInterceptor.invoke( (CacheOperationInvocationContext) context, adapter); } else { - throw new IllegalArgumentException("Could not handle " + operation); + throw new IllegalArgumentException("Cannot handle " + operation); } } diff --git a/spring-context-support/src/main/java/org/springframework/scheduling/quartz/SchedulerFactoryBean.java b/spring-context-support/src/main/java/org/springframework/scheduling/quartz/SchedulerFactoryBean.java index d3d7e64347f..5d5da85fb81 100644 --- a/spring-context-support/src/main/java/org/springframework/scheduling/quartz/SchedulerFactoryBean.java +++ b/spring-context-support/src/main/java/org/springframework/scheduling/quartz/SchedulerFactoryBean.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -43,7 +43,6 @@ import org.springframework.core.io.Resource; import org.springframework.core.io.ResourceLoader; import org.springframework.core.io.support.PropertiesLoaderUtils; import org.springframework.scheduling.SchedulingException; -import org.springframework.util.Assert; import org.springframework.util.CollectionUtils; /** @@ -105,6 +104,7 @@ public class SchedulerFactoryBean extends SchedulerAccessor implements FactoryBe private static final ThreadLocal configTimeNonTransactionalDataSourceHolder = new ThreadLocal<>(); + /** * Return the ResourceLoader for the currently configured Quartz Scheduler, * to be used by ResourceLoaderClassLoadHelper. @@ -210,7 +210,6 @@ public class SchedulerFactoryBean extends SchedulerAccessor implements FactoryBe * @see #setQuartzProperties */ public void setSchedulerFactoryClass(Class schedulerFactoryClass) { - Assert.isAssignable(SchedulerFactory.class, schedulerFactoryClass); this.schedulerFactoryClass = schedulerFactoryClass; } diff --git a/spring-context-support/src/test/java/org/springframework/cache/jcache/interceptor/CacheResolverAdapterTests.java b/spring-context-support/src/test/java/org/springframework/cache/jcache/interceptor/CacheResolverAdapterTests.java index 8f9031c811f..56fc64be855 100644 --- a/spring-context-support/src/test/java/org/springframework/cache/jcache/interceptor/CacheResolverAdapterTests.java +++ b/spring-context-support/src/test/java/org/springframework/cache/jcache/interceptor/CacheResolverAdapterTests.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -30,8 +30,6 @@ import org.junit.rules.ExpectedException; import org.springframework.cache.Cache; import org.springframework.cache.jcache.AbstractJCacheTests; -import org.springframework.util.Assert; -import org.springframework.util.ReflectionUtils; import static org.junit.Assert.*; import static org.mockito.BDDMockito.*; @@ -46,7 +44,7 @@ public class CacheResolverAdapterTests extends AbstractJCacheTests { @Test - public void resolveSimpleCache() { + public void resolveSimpleCache() throws Exception { DefaultCacheInvocationContext dummyContext = createDummyContext(); CacheResolverAdapter adapter = new CacheResolverAdapter(getCacheResolver(dummyContext, "testCache")); Collection caches = adapter.resolveCaches(dummyContext); @@ -56,7 +54,7 @@ public class CacheResolverAdapterTests extends AbstractJCacheTests { } @Test - public void resolveUnknownCache() { + public void resolveUnknownCache() throws Exception { DefaultCacheInvocationContext dummyContext = createDummyContext(); CacheResolverAdapter adapter = new CacheResolverAdapter(getCacheResolver(dummyContext, null)); @@ -66,7 +64,7 @@ public class CacheResolverAdapterTests extends AbstractJCacheTests { protected CacheResolver getCacheResolver(CacheInvocationContext context, String cacheName) { CacheResolver cacheResolver = mock(CacheResolver.class); - final javax.cache.Cache cache; + javax.cache.Cache cache; if (cacheName == null) { cache = null; } @@ -78,9 +76,8 @@ public class CacheResolverAdapterTests extends AbstractJCacheTests { return cacheResolver; } - protected DefaultCacheInvocationContext createDummyContext() { - Method method = ReflectionUtils.findMethod(Sample.class, "get", String.class); - Assert.notNull(method); + protected DefaultCacheInvocationContext createDummyContext() throws Exception { + Method method = Sample.class.getMethod("get", String.class); CacheResult cacheAnnotation = method.getAnnotation(CacheResult.class); CacheMethodDetails methodDetails = new DefaultCacheMethodDetails<>(method, cacheAnnotation, "test"); @@ -93,7 +90,7 @@ public class CacheResolverAdapterTests extends AbstractJCacheTests { static class Sample { @CacheResult - private Object get(String id) { + public Object get(String id) { return null; } } diff --git a/spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperation.java b/spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperation.java index dca82086670..6898fa35d5b 100644 --- a/spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperation.java +++ b/spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperation.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -145,19 +145,19 @@ public abstract class CacheOperation implements BasicOperation { private String condition = ""; public void setName(String name) { - Assert.hasText(name); + Assert.hasText(name, "Name must not be empty"); this.name = name; } public void setCacheName(String cacheName) { - Assert.hasText(cacheName); + Assert.hasText(cacheName, "Cache name must not be empty"); this.cacheNames = Collections.singleton(cacheName); } public void setCacheNames(String... cacheNames) { this.cacheNames = new LinkedHashSet<>(cacheNames.length); for (String cacheName : cacheNames) { - Assert.hasText(cacheName, "Cache name must be non-null if specified"); + Assert.hasText(cacheName, "Cache name must be non-empty if specified"); this.cacheNames.add(cacheName); } } @@ -167,7 +167,7 @@ public abstract class CacheOperation implements BasicOperation { } public void setKey(String key) { - Assert.notNull(key); + Assert.notNull(key, "Key must not be null"); this.key = key; } @@ -188,22 +188,22 @@ public abstract class CacheOperation implements BasicOperation { } public void setKeyGenerator(String keyGenerator) { - Assert.notNull(keyGenerator); + Assert.notNull(keyGenerator, "KeyGenerator name must not be null"); this.keyGenerator = keyGenerator; } public void setCacheManager(String cacheManager) { - Assert.notNull(cacheManager); + Assert.notNull(cacheManager, "CacheManager name must not be null"); this.cacheManager = cacheManager; } public void setCacheResolver(String cacheResolver) { - Assert.notNull(this.cacheManager); + Assert.notNull(cacheResolver, "CacheResolver name must not be null"); this.cacheResolver = cacheResolver; } public void setCondition(String condition) { - Assert.notNull(condition); + Assert.notNull(condition, "Condition must not be null"); this.condition = condition; } diff --git a/spring-context/src/main/java/org/springframework/context/annotation/ComponentScanAnnotationParser.java b/spring-context/src/main/java/org/springframework/context/annotation/ComponentScanAnnotationParser.java index fc095c9a078..07628c50a50 100644 --- a/spring-context/src/main/java/org/springframework/context/annotation/ComponentScanAnnotationParser.java +++ b/spring-context/src/main/java/org/springframework/context/annotation/ComponentScanAnnotationParser.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -143,7 +143,7 @@ class ComponentScanAnnotationParser { switch (filterType) { case ANNOTATION: Assert.isAssignable(Annotation.class, filterClass, - "An error occurred while processing a @ComponentScan ANNOTATION type filter: "); + "@ComponentScan ANNOTATION type filter requires an annotation type"); @SuppressWarnings("unchecked") Class annotationType = (Class) filterClass; typeFilters.add(new AnnotationTypeFilter(annotationType)); @@ -153,7 +153,7 @@ class ComponentScanAnnotationParser { break; case CUSTOM: Assert.isAssignable(TypeFilter.class, filterClass, - "An error occurred while processing a @ComponentScan CUSTOM type filter: "); + "@ComponentScan CUSTOM type filter requires a TypeFilter implementation"); TypeFilter filter = BeanUtils.instantiateClass(filterClass, TypeFilter.class); ParserStrategyUtils.invokeAwareMethods( filter, this.environment, this.resourceLoader, this.registry); diff --git a/spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java b/spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java index 3c99a43dcc5..0af556507c3 100644 --- a/spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java +++ b/spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -39,7 +39,6 @@ import org.springframework.context.Lifecycle; import org.springframework.context.LifecycleProcessor; import org.springframework.context.Phased; import org.springframework.context.SmartLifecycle; -import org.springframework.util.Assert; /** * Default implementation of the {@link LifecycleProcessor} strategy. @@ -70,7 +69,10 @@ public class DefaultLifecycleProcessor implements LifecycleProcessor, BeanFactor @Override public void setBeanFactory(BeanFactory beanFactory) { - Assert.isInstanceOf(ConfigurableListableBeanFactory.class, beanFactory); + if (!(beanFactory instanceof ConfigurableListableBeanFactory)) { + throw new IllegalArgumentException( + "DefaultLifecycleProcessor requires a ConfigurableListableBeanFactory: " + beanFactory); + } this.beanFactory = (ConfigurableListableBeanFactory) beanFactory; } diff --git a/spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactory.java b/spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactory.java index 70cb9acf0eb..18f10bdfada 100644 --- a/spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactory.java +++ b/spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactory.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -126,7 +126,7 @@ public class DateTimeFormatterFactory { * @param style two characters from the set {"S", "M", "L", "F", "-"} */ public void setStylePattern(String style) { - Assert.isTrue(style != null && style.length() == 2); + Assert.isTrue(style != null && style.length() == 2, "Style pattern must consist of two characters"); this.dateStyle = convertStyleCharacter(style.charAt(0)); this.timeStyle = convertStyleCharacter(style.charAt(1)); } diff --git a/spring-context/src/main/java/org/springframework/instrument/classloading/weblogic/WebLogicClassLoaderAdapter.java b/spring-context/src/main/java/org/springframework/instrument/classloading/weblogic/WebLogicClassLoaderAdapter.java index 2f741205909..7a2a74afda5 100644 --- a/spring-context/src/main/java/org/springframework/instrument/classloading/weblogic/WebLogicClassLoaderAdapter.java +++ b/spring-context/src/main/java/org/springframework/instrument/classloading/weblogic/WebLogicClassLoaderAdapter.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2012 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -55,7 +55,7 @@ class WebLogicClassLoaderAdapter { public WebLogicClassLoaderAdapter(ClassLoader classLoader) { - Class wlGenericClassLoaderClass = null; + Class wlGenericClassLoaderClass; try { wlGenericClassLoaderClass = classLoader.loadClass(GENERIC_CLASS_LOADER_NAME); this.wlPreProcessorClass = classLoader.loadClass(CLASS_PRE_PROCESSOR_NAME); @@ -66,12 +66,14 @@ class WebLogicClassLoaderAdapter { this.wlGenericClassLoaderConstructor = wlGenericClassLoaderClass.getConstructor( this.getClassFinderMethod.getReturnType(), ClassLoader.class); } - catch (Exception ex) { + catch (Throwable ex) { throw new IllegalStateException( "Could not initialize WebLogic LoadTimeWeaver because WebLogic 10 API classes are not available", ex); } - Assert.isInstanceOf(wlGenericClassLoaderClass, classLoader, - "ClassLoader must be instance of [" + wlGenericClassLoaderClass.getName() + "]"); + if (!wlGenericClassLoaderClass.isInstance(classLoader)) { + throw new IllegalArgumentException( + "ClassLoader must be an instance of [" + wlGenericClassLoaderClass.getName() + "]: " + classLoader); + } this.classLoader = classLoader; } @@ -87,7 +89,7 @@ class WebLogicClassLoaderAdapter { catch (InvocationTargetException ex) { throw new IllegalStateException("WebLogic addInstanceClassPreProcessor method threw exception", ex.getCause()); } - catch (Exception ex) { + catch (Throwable ex) { throw new IllegalStateException("Could not invoke WebLogic addInstanceClassPreProcessor method", ex); } } @@ -106,8 +108,9 @@ class WebLogicClassLoaderAdapter { catch (InvocationTargetException ex) { throw new IllegalStateException("WebLogic GenericClassLoader constructor failed", ex.getCause()); } - catch (Exception ex) { + catch (Throwable ex) { throw new IllegalStateException("Could not construct WebLogic GenericClassLoader", ex); } } + } diff --git a/spring-context/src/test/java/org/springframework/aop/framework/ClassWithComplexConstructor.java b/spring-context/src/test/java/org/springframework/aop/framework/ClassWithComplexConstructor.java index 19bb244bff0..2d17df795b3 100644 --- a/spring-context/src/test/java/org/springframework/aop/framework/ClassWithComplexConstructor.java +++ b/spring-context/src/test/java/org/springframework/aop/framework/ClassWithComplexConstructor.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -33,7 +33,7 @@ public class ClassWithComplexConstructor { @Autowired public ClassWithComplexConstructor(Dependency dependency) { - Assert.notNull(dependency); + Assert.notNull(dependency, "No Dependency bean injected"); this.dependency = dependency; } @@ -42,7 +42,8 @@ public class ClassWithComplexConstructor { } public void method() { - Assert.isTrue(this.selfReference != this && AopUtils.isCglibProxy(this.selfReference)); + Assert.state(this.selfReference != this && AopUtils.isCglibProxy(this.selfReference), + "Self reference must be a CGLIB proxy"); this.dependency.method(); } diff --git a/spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java b/spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java index 25da88cf3fb..a8eec500df2 100644 --- a/spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java +++ b/spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -1250,7 +1250,7 @@ public class ConfigurationClassPostProcessorTests { @PostConstruct public void validate() { - Assert.notNull(provider); + Assert.notNull(provider, "No ServiceBeanProvider injected"); } } @@ -1291,7 +1291,7 @@ public class ConfigurationClassPostProcessorTests { @PostConstruct public void validate() { - Assert.notNull(provider); + Assert.notNull(provider, "No ServiceBeanProvider injected"); } } @@ -1403,7 +1403,7 @@ public class ConfigurationClassPostProcessorTests { static class DependingFoo { DependingFoo(BarArgument bar) { - Assert.notNull(bar); + Assert.notNull(bar, "No BarArgument injected"); } } diff --git a/spring-context/src/test/java/org/springframework/context/support/Service.java b/spring-context/src/test/java/org/springframework/context/support/Service.java index ee9d5095d74..dd9fcd3182f 100644 --- a/spring-context/src/test/java/org/springframework/context/support/Service.java +++ b/spring-context/src/test/java/org/springframework/context/support/Service.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2012 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -72,7 +72,8 @@ public class Service implements ApplicationContextAware, MessageSourceAware, Dis Thread thread = new Thread() { @Override public void run() { - Assert.isTrue(applicationContext.getBean("messageSource") instanceof StaticMessageSource); + Assert.state(applicationContext.getBean("messageSource") instanceof StaticMessageSource, + "Invalid MessageSource bean"); try { applicationContext.getBean("service2"); // Should have thrown BeanCreationNotAllowedException diff --git a/spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java b/spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java index 2eda9eddd89..75e6515a69c 100644 --- a/spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java +++ b/spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -355,6 +355,7 @@ public class DateTimeFormattingTests { } @Test + @SuppressWarnings("deprecation") public void testBindInstantFromJavaUtilDate() throws Exception { MutablePropertyValues propertyValues = new MutablePropertyValues(); propertyValues.add("instant", new Date(109, 9, 31, 12, 0)); diff --git a/spring-context/src/test/java/org/springframework/validation/beanvalidation/SpringValidatorAdapterTests.java b/spring-context/src/test/java/org/springframework/validation/beanvalidation/SpringValidatorAdapterTests.java index de7bc833a1d..5cd539f971b 100644 --- a/spring-context/src/test/java/org/springframework/validation/beanvalidation/SpringValidatorAdapterTests.java +++ b/spring-context/src/test/java/org/springframework/validation/beanvalidation/SpringValidatorAdapterTests.java @@ -240,7 +240,7 @@ public class SpringValidatorAdapterTests { else { context.disableDefaultConstraintViolation(); context.buildConstraintViolationWithTemplate(message) - .addNode(field) + .addPropertyNode(field) .addConstraintViolation(); return false; } diff --git a/spring-core/src/main/java/org/springframework/core/Constants.java b/spring-core/src/main/java/org/springframework/core/Constants.java index 4b9d6936c6f..5045d09a523 100644 --- a/spring-core/src/main/java/org/springframework/core/Constants.java +++ b/spring-core/src/main/java/org/springframework/core/Constants.java @@ -59,7 +59,7 @@ public class Constants { * @throws IllegalArgumentException if the supplied {@code clazz} is {@code null} */ public Constants(Class clazz) { - Assert.notNull(clazz); + Assert.notNull(clazz, "Class must not be null"); this.className = clazz.getName(); Field[] fields = clazz.getFields(); for (Field field : fields) { diff --git a/spring-core/src/main/java/org/springframework/core/ParameterizedTypeReference.java b/spring-core/src/main/java/org/springframework/core/ParameterizedTypeReference.java index f3d516702fd..dcb9c29591b 100644 --- a/spring-core/src/main/java/org/springframework/core/ParameterizedTypeReference.java +++ b/spring-core/src/main/java/org/springframework/core/ParameterizedTypeReference.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2013 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -47,9 +47,9 @@ public abstract class ParameterizedTypeReference { protected ParameterizedTypeReference() { Class parameterizedTypeReferenceSubclass = findParameterizedTypeReferenceSubclass(getClass()); Type type = parameterizedTypeReferenceSubclass.getGenericSuperclass(); - Assert.isInstanceOf(ParameterizedType.class, type); + Assert.isInstanceOf(ParameterizedType.class, type, "Type must be a parameterized type"); ParameterizedType parameterizedType = (ParameterizedType) type; - Assert.isTrue(parameterizedType.getActualTypeArguments().length == 1); + Assert.isTrue(parameterizedType.getActualTypeArguments().length == 1, "Number of type arguments must be 1"); this.type = parameterizedType.getActualTypeArguments()[0]; } diff --git a/spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java b/spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java index e91b6a6394f..8980236f63b 100644 --- a/spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java +++ b/spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -408,7 +408,10 @@ abstract class SerializableTypeWrapper { private void readObject(ObjectInputStream inputStream) throws IOException, ClassNotFoundException { inputStream.defaultReadObject(); this.method = ReflectionUtils.findMethod(this.declaringClass, this.methodName); - Assert.state(Type.class == this.method.getReturnType() || Type[].class == this.method.getReturnType()); + if (this.method.getReturnType() != Type.class && this.method.getReturnType() != Type[].class) { + throw new IllegalStateException( + "Invalid return type on deserialized method - needs to be Type or Type[]: " + this.method); + } } } diff --git a/spring-core/src/main/java/org/springframework/core/env/JOptCommandLinePropertySource.java b/spring-core/src/main/java/org/springframework/core/env/JOptCommandLinePropertySource.java index 9b3fa2668c2..19733690e5d 100644 --- a/spring-core/src/main/java/org/springframework/core/env/JOptCommandLinePropertySource.java +++ b/spring-core/src/main/java/org/springframework/core/env/JOptCommandLinePropertySource.java @@ -1,5 +1,5 @@ /* - * Copyright 2002-2016 the original author or authors. + * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -23,15 +23,15 @@ import java.util.List; import joptsimple.OptionSet; import joptsimple.OptionSpec; -import org.springframework.util.Assert; - /** * {@link CommandLinePropertySource} implementation backed by a JOpt {@link OptionSet}. * *

Typical usage

+ * * Configure and execute an {@code OptionParser} against the {@code String[]} of arguments * supplied to the {@code main} method, and create a {@link JOptCommandLinePropertySource} * using the resulting {@code OptionSet} object: + * * 
  * public static void main(String[] args) {
  *     OptionParser parser = new OptionParser();
@@ -44,7 +44,7 @@ import org.springframework.util.Assert;
  *
  * See {@link CommandLinePropertySource} for complete general usage examples.
  *
- * 
Requires JOpt version 4.3 or higher. Tested against JOpt up until 4.6.
+ * 
Requires JOpt Simple version 4.3 or higher. Tested against JOpt up until 5.0.
  *
  * @author Chris Beams
  * @author Juergen Hoeller
@@ -98,7 +98,7 @@ public class JOptCommandLinePropertySource extends CommandLinePropertySource argValues = this.source.valuesOf(name);
 		List stringArgValues = new ArrayList<>();
 		for (Object argValue : argValues) {
-			stringArgValues.add(argValue instanceof String ? (String) argValue : argValue.toString());
+			stringArgValues.add(argValue.toString());
 		}
 		if (stringArgValues.isEmpty()) {
 			return (this.source.has(name) ? Collections.emptyList() : null);
@@ -111,8 +111,7 @@ public class JOptCommandLinePropertySource extends CommandLinePropertySource argValues = this.source.nonOptionArguments();
 		List stringArgValues = new ArrayList<>();
 		for (Object argValue : argValues) {
-			Assert.isInstanceOf(String.class, argValue, "Argument values must be of type String");
-			stringArgValues.add((String) argValue);
+			stringArgValues.add(argValue.toString());
 		}
 		return (stringArgValues.isEmpty() ? Collections.emptyList() :
 				Collections.unmodifiableList(stringArgValues));
diff --git a/spring-core/src/main/java/org/springframework/util/Assert.java b/spring-core/src/main/java/org/springframework/util/Assert.java
index 24d54d1fb4f..581f9e93d11 100644
--- a/spring-core/src/main/java/org/springframework/util/Assert.java
+++ b/spring-core/src/main/java/org/springframework/util/Assert.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,9 +49,9 @@ import java.util.function.Supplier;
  *
  * @author Keith Donald
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @author Colin Sampaleanu
  * @author Rob Harrop
- * @author Sam Brannen
  * @since 1.1.2
  */
 public abstract class Assert {
@@ -66,6 +66,7 @@ public abstract class Assert {
 	 * @param messageSupplier a supplier for the exception message to use if the
 	 * assertion fails
 	 * @throws IllegalArgumentException if {@code expression} is {@code false}
+	 * @since 5.0
 	 */
 	public static void isTrue(boolean expression, Supplier messageSupplier) {
 		if (!expression) {
@@ -87,17 +88,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert a boolean expression, throwing an {@code IllegalArgumentException}
-	 * if the expression evaluates to {@code false}.
-	 * 
Assert.isTrue(i > 0);

-	 * @param expression a boolean expression
-	 * @throws IllegalArgumentException if {@code expression} is {@code false}
-	 */
-	public static void isTrue(boolean expression) {
-		isTrue(expression, "[Assertion failed] - this expression must be true");
-	}
-
 	/**
 	 * Assert that an object is {@code null}.
 	 * 
@@ -107,6 +97,7 @@ public abstract class Assert {
 	 * @param messageSupplier a supplier for the exception message to use if the
 	 * assertion fails
 	 * @throws IllegalArgumentException if the object is not {@code null}
+	 * @since 5.0
 	 */
 	public static void isNull(Object object, Supplier messageSupplier) {
 		if (object != null) {
@@ -127,16 +118,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert that an object is {@code null}.
-	 * 
Assert.isNull(value);

-	 * @param object the object to check
-	 * @throws IllegalArgumentException if the object is not {@code null}
-	 */
-	public static void isNull(Object object) {
-		isNull(object, "[Assertion failed] - the object argument must be null");
-	}
-
 	/**
 	 * Assert that an object is not {@code null}.
 	 * 
@@ -146,6 +127,7 @@ public abstract class Assert {
 	 * @param messageSupplier a supplier for the exception message to use if the
 	 * assertion fails
 	 * @throws IllegalArgumentException if the object is {@code null}
+	 * @since 5.0
 	 */
 	public static void notNull(Object object, Supplier messageSupplier) {
 		if (object == null) {
@@ -166,16 +148,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert that an object is not {@code null}.
-	 * 
Assert.notNull(clazz);

-	 * @param object the object to check
-	 * @throws IllegalArgumentException if the object is {@code null}
-	 */
-	public static void notNull(Object object) {
-		notNull(object, "[Assertion failed] - this argument is required; it must not be null");
-	}
-
 	/**
 	 * Assert that the given String is not empty; that is,
 	 * it must not be {@code null} and not the empty String.
@@ -187,6 +159,7 @@ public abstract class Assert {
 	 * assertion fails
 	 * @see StringUtils#hasLength
 	 * @throws IllegalArgumentException if the text is empty
+	 * @since 5.0
 	 */
 	public static void hasLength(String text, Supplier messageSupplier) {
 		if (!StringUtils.hasLength(text)) {
@@ -209,19 +182,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert that the given String is not empty; that is,
-	 * it must not be {@code null} and not the empty String.
-	 * 
Assert.hasLength(name);

-	 * @param text the String to check
-	 * @see StringUtils#hasLength
-	 * @throws IllegalArgumentException if the text is empty
-	 */
-	public static void hasLength(String text) {
-		hasLength(text,
-				"[Assertion failed] - this String argument must have length; it must not be null or empty");
-	}
-
 	/**
 	 * Assert that the given String contains valid text content; that is, it must not
 	 * be {@code null} and must contain at least one non-whitespace character.
@@ -233,6 +193,7 @@ public abstract class Assert {
 	 * assertion fails
 	 * @see StringUtils#hasText
 	 * @throws IllegalArgumentException if the text does not contain valid text content
+	 * @since 5.0
 	 */
 	public static void hasText(String text, Supplier messageSupplier) {
 		if (!StringUtils.hasText(text)) {
@@ -255,19 +216,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert that the given String contains valid text content; that is, it must not
-	 * be {@code null} and must contain at least one non-whitespace character.
-	 * 
Assert.hasText(name, "'name' must not be empty");

-	 * @param text the String to check
-	 * @see StringUtils#hasText
-	 * @throws IllegalArgumentException if the text does not contain valid text content
-	 */
-	public static void hasText(String text) {
-		hasText(text,
-				"[Assertion failed] - this String argument must have text; it must not be null, empty, or blank");
-	}
-
 	/**
 	 * Assert that the given text does not contain the given substring.
 	 * 
@@ -278,6 +226,7 @@ public abstract class Assert {
 	 * @param messageSupplier a supplier for the exception message to use if the
 	 * assertion fails
 	 * @throws IllegalArgumentException if the text contains the substring
+	 * @since 5.0
 	 */
 	public static void doesNotContain(String textToSearch, String substring, Supplier messageSupplier) {
 		if (StringUtils.hasLength(textToSearch) && StringUtils.hasLength(substring) &&
@@ -301,18 +250,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert that the given text does not contain the given substring.
-	 * 
Assert.doesNotContain(name, "rod");

-	 * @param textToSearch the text to search
-	 * @param substring the substring to find within the text
-	 * @throws IllegalArgumentException if the text contains the substring
-	 */
-	public static void doesNotContain(String textToSearch, String substring) {
-		doesNotContain(textToSearch, substring,
-				() -> "[Assertion failed] - this String argument must not contain the substring [" + substring + "]");
-	}
-
 	/**
 	 * Assert that an array contains elements; that is, it must not be
 	 * {@code null} and must contain at least one element.
@@ -323,6 +260,7 @@ public abstract class Assert {
 	 * @param messageSupplier a supplier for the exception message to use if the
 	 * assertion fails
 	 * @throws IllegalArgumentException if the object array is {@code null} or contains no elements
+	 * @since 5.0
 	 */
 	public static void notEmpty(Object[] array, Supplier messageSupplier) {
 		if (ObjectUtils.isEmpty(array)) {
@@ -344,18 +282,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert that an array contains elements; that is, it must not be
-	 * {@code null} and must contain at least one element.
-	 * 
Assert.notEmpty(array);

-	 * @param array the array to check
-	 * @throws IllegalArgumentException if the object array is {@code null} or
-	 * contains no elements
-	 */
-	public static void notEmpty(Object[] array) {
-		notEmpty(array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element");
-	}
-
 	/**
 	 * Assert that an array contains no {@code null} elements.
 	 * 
Note: Does not complain if the array is empty!
@@ -366,6 +292,7 @@ public abstract class Assert {
 	 * @param messageSupplier a supplier for the exception message to use if the
 	 * assertion fails
 	 * @throws IllegalArgumentException if the object array contains a {@code null} element
+	 * @since 5.0
 	 */
 	public static void noNullElements(Object[] array, Supplier messageSupplier) {
 		if (array != null) {
@@ -395,17 +322,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert that an array contains no {@code null} elements.
-	 * 
Note: Does not complain if the array is empty!
-	 * 
Assert.noNullElements(array);

-	 * @param array the array to check
-	 * @throws IllegalArgumentException if the object array contains a {@code null} element
-	 */
-	public static void noNullElements(Object[] array) {
-		noNullElements(array, "[Assertion failed] - this array must not contain any null elements");
-	}
-
 	/**
 	 * Assert that a collection contains elements; that is, it must not be
 	 * {@code null} and must contain at least one element.
@@ -417,6 +333,7 @@ public abstract class Assert {
 	 * assertion fails
 	 * @throws IllegalArgumentException if the collection is {@code null} or
 	 * contains no elements
+	 * @since 5.0
 	 */
 	public static void notEmpty(Collection collection, Supplier messageSupplier) {
 		if (CollectionUtils.isEmpty(collection)) {
@@ -439,19 +356,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert that a collection contains elements; that is, it must not be
-	 * {@code null} and must contain at least one element.
-	 * 
Assert.notEmpty(collection, "Collection must contain elements");

-	 * @param collection the collection to check
-	 * @throws IllegalArgumentException if the collection is {@code null} or
-	 * contains no elements
-	 */
-	public static void notEmpty(Collection collection) {
-		notEmpty(collection,
-				"[Assertion failed] - this collection must not be empty: it must contain at least 1 element");
-	}
-
 	/**
 	 * Assert that a Map contains entries; that is, it must not be {@code null}
 	 * and must contain at least one entry.
@@ -462,6 +366,7 @@ public abstract class Assert {
 	 * @param messageSupplier a supplier for the exception message to use if the
 	 * assertion fails
 	 * @throws IllegalArgumentException if the map is {@code null} or contains no entries
+	 * @since 5.0
 	 */
 	public static void notEmpty(Map map, Supplier messageSupplier) {
 		if (CollectionUtils.isEmpty(map)) {
@@ -483,29 +388,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert that a Map contains entries; that is, it must not be {@code null}
-	 * and must contain at least one entry.
-	 * 
Assert.notEmpty(map);

-	 * @param map the map to check
-	 * @throws IllegalArgumentException if the map is {@code null} or contains no entries
-	 */
-	public static void notEmpty(Map map) {
-		notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");
-	}
-
-	/**
-	 * Assert that the provided object is an instance of the provided class.
-	 * 
Assert.instanceOf(Foo.class, foo);

-	 * @param type the type to check against
-	 * @param obj the object to check
-	 * @throws IllegalArgumentException if the object is not an instance of type
-	 * @see Class#isInstance
-	 */
-	public static void isInstanceOf(Class type, Object obj) {
-		isInstanceOf(type, obj, "");
-	}
-
 	/**
 	 * Assert that the provided object is an instance of the provided class.
 	 * 
@@ -519,11 +401,12 @@ public abstract class Assert {
 	 * in ":" or "." so that the generated message looks OK when appended to it.
 	 * @throws IllegalArgumentException if the object is not an instance of type
 	 * @see Class#isInstance
+	 * @since 5.0
 	 */
 	public static void isInstanceOf(Class type, Object obj, Supplier messageSupplier) {
 		notNull(type, "Type to check against must not be null");
 		if (!type.isInstance(obj)) {
-			isInstanceCheckFailed(type, obj, nullSafeGet(messageSupplier));
+			instanceCheckFailed(type, obj, nullSafeGet(messageSupplier));
 		}
 	}
 
@@ -541,26 +424,26 @@ public abstract class Assert {
 	public static void isInstanceOf(Class type, Object obj, String message) {
 		notNull(type, "Type to check against must not be null");
 		if (!type.isInstance(obj)) {
-			isInstanceCheckFailed(type, obj, message);
+			instanceCheckFailed(type, obj, message);
 		}
 	}
 
-	private static void isInstanceCheckFailed(Class type, Object obj, String message) {
-		throw new IllegalArgumentException(
-				(StringUtils.hasLength(message) ? message + " " : "") +
-				"Object of class [" + (obj != null ? obj.getClass().getName() : "null") +
-				"] must be an instance of " + type);
-	}
-
 	/**
-	 * Assert that {@code superType.isAssignableFrom(subType)} is {@code true}.
-	 * 
Assert.isAssignable(Number.class, myClass);

-	 * @param superType the super type to check
-	 * @param subType the sub type to check
-	 * @throws IllegalArgumentException if the classes are not assignable
+	 * Assert that the provided object is an instance of the provided class.
+	 * 
Assert.instanceOf(Foo.class, foo);

+	 * @param type the type to check against
+	 * @param obj the object to check
+	 * @throws IllegalArgumentException if the object is not an instance of type
+	 * @see Class#isInstance
 	 */
-	public static void isAssignable(Class superType, Class subType) {
-		isAssignable(superType, subType, "");
+	public static void isInstanceOf(Class type, Object obj) {
+		isInstanceOf(type, obj, "");
+	}
+
+	private static void instanceCheckFailed(Class type, Object obj, String message) {
+		String className = (obj != null ? obj.getClass().getName() : "null");
+		throw new IllegalArgumentException(StringUtils.hasLength(message) ? message + ": " + className :
+				"Object of class [" + className + "] must be an instance of " + type);
 	}
 
 	/**
@@ -575,11 +458,12 @@ public abstract class Assert {
 	 * by this method in order to provide further context. It should normally end
 	 * in ":" or "." so that the generated message looks OK when appended to it.
 	 * @throws IllegalArgumentException if the classes are not assignable
+	 * @since 5.0
 	 */
 	public static void isAssignable(Class superType, Class subType, Supplier messageSupplier) {
 		notNull(superType, "Super type to check against must not be null");
 		if (subType == null || !superType.isAssignableFrom(subType)) {
-			isAssignableCheckFailed(superType, subType, nullSafeGet(messageSupplier));
+			assignableCheckFailed(superType, subType, nullSafeGet(messageSupplier));
 		}
 	}
 
@@ -596,12 +480,23 @@ public abstract class Assert {
 	public static void isAssignable(Class superType, Class subType, String message) {
 		notNull(superType, "Super type to check against must not be null");
 		if (subType == null || !superType.isAssignableFrom(subType)) {
-			isAssignableCheckFailed(superType, subType, message);
+			assignableCheckFailed(superType, subType, message);
 		}
 	}
 
-	private static void isAssignableCheckFailed(Class superType, Class subType, String message) {
-		throw new IllegalArgumentException((StringUtils.hasLength(message) ? message + " " : "") +
+	/**
+	 * Assert that {@code superType.isAssignableFrom(subType)} is {@code true}.
+	 * 
Assert.isAssignable(Number.class, myClass);

+	 * @param superType the super type to check
+	 * @param subType the sub type to check
+	 * @throws IllegalArgumentException if the classes are not assignable
+	 */
+	public static void isAssignable(Class superType, Class subType) {
+		isAssignable(superType, subType, "");
+	}
+
+	private static void assignableCheckFailed(Class superType, Class subType, String message) {
+		throw new IllegalArgumentException(StringUtils.hasLength(message) ? message + ": " + subType :
 				subType + " is not assignable to " + superType);
 	}
 
@@ -618,6 +513,7 @@ public abstract class Assert {
 	 * @param messageSupplier a supplier for the exception message to use if the
 	 * assertion fails
 	 * @throws IllegalStateException if {@code expression} is {@code false}
+	 * @since 5.0
 	 */
 	public static void state(boolean expression, Supplier messageSupplier) {
 		if (!expression) {
@@ -641,19 +537,6 @@ public abstract class Assert {
 		}
 	}
 
-	/**
-	 * Assert a boolean expression, throwing an {@link IllegalStateException}
-	 * if the expression evaluates to {@code false}.
-	 * 
Call {@link #isTrue} if you wish to throw an {@code IllegalArgumentException}
-	 * on an assertion failure.
-	 * 
Assert.state(id == null);

-	 * @param expression a boolean expression
-	 * @throws IllegalStateException if {@code expression} is {@code false}
-	 */
-	public static void state(boolean expression) {
-		state(expression, "[Assertion failed] - this state invariant must be true");
-	}
-
 	private static String nullSafeGet(Supplier messageSupplier) {
 		return (messageSupplier != null ? messageSupplier.get() : null);
 	}
diff --git a/spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java b/spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java
index af1e5baedb3..b394d90b3e5 100644
--- a/spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java
+++ b/spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -903,7 +903,7 @@ public class ConcurrentReferenceHashMap extends AbstractMap implemen
 
 		@Override
 		public void remove() {
-			Assert.state(this.last != null);
+			Assert.state(this.last != null, "No element to remove");
 			ConcurrentReferenceHashMap.this.remove(this.last.getKey());
 		}
 	}
diff --git a/spring-core/src/test/java/org/springframework/util/AssertTests.java b/spring-core/src/test/java/org/springframework/util/AssertTests.java
index 8da0f6a2536..079e4c4c30f 100644
--- a/spring-core/src/test/java/org/springframework/util/AssertTests.java
+++ b/spring-core/src/test/java/org/springframework/util/AssertTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,6 +35,7 @@ import static org.hamcrest.CoreMatchers.*;
  * @author Rick Evans
  * @author Arjen Poutsma
  * @author Sam Brannen
+ * @author Juergen Hoeller
  */
 public class AssertTests {
 
@@ -43,14 +44,15 @@ public class AssertTests {
 
 
 	@Test
-	public void isTrue() {
-		Assert.isTrue(true);
+	public void isTrueWithMessage() {
+		Assert.isTrue(true, "enigma");
 	}
 
 	@Test
-	public void isTrueWithFalseExpression() {
+	public void isTrueWithFalse() {
 		thrown.expect(IllegalArgumentException.class);
-		Assert.isTrue(false);
+		thrown.expectMessage("enigma");
+		Assert.isTrue(false, "enigma");
 	}
 
 	@Test
@@ -72,22 +74,11 @@ public class AssertTests {
 		Assert.isTrue(false, (Supplier) null);
 	}
 
-	@Test
-	public void isNull() {
-		Assert.isNull(null);
-	}
-
 	@Test
 	public void isNullWithMessage() {
 		Assert.isNull(null, "Bla");
 	}
 
-	@Test
-	public void isNullWithNonNullObject() {
-		thrown.expect(IllegalArgumentException.class);
-		Assert.isNull(new Object());
-	}
-
 	@Test
 	public void isNullWithMessageSupplier() {
 		Assert.isNull(null, () -> "enigma");
@@ -108,8 +99,8 @@ public class AssertTests {
 	}
 
 	@Test
-	public void notNull() {
-		Assert.notNull("foo");
+	public void notNullWithMessage() {
+		Assert.notNull("foo", "enigma");
 	}
 
 	@Test
@@ -133,24 +124,26 @@ public class AssertTests {
 
 	@Test
 	public void hasLength() {
-		Assert.hasLength("I Heart ...");
+		Assert.hasLength("I Heart ...", "enigma");
 	}
 
 	@Test
 	public void hasLengthWithWhitespaceOnly() {
-		Assert.hasLength("\t  ");
+		Assert.hasLength("\t  ", "enigma");
 	}
 
 	@Test
 	public void hasLengthWithEmptyString() {
 		thrown.expect(IllegalArgumentException.class);
-		Assert.hasLength("");
+		thrown.expectMessage("enigma");
+		Assert.hasLength("", "enigma");
 	}
 
 	@Test
 	public void hasLengthWithNull() {
 		thrown.expect(IllegalArgumentException.class);
-		Assert.hasLength(null);
+		thrown.expectMessage("enigma");
+		Assert.hasLength(null, "enigma");
 	}
 
 	@Test
@@ -186,7 +179,7 @@ public class AssertTests {
 
 	@Test
 	public void hasText() {
-		Assert.hasText("foo");
+		Assert.hasText("foo", "enigma");
 	}
 
 	@Test
@@ -204,7 +197,7 @@ public class AssertTests {
 	}
 
 	@Test
-	public void hasTextWithNullAndMessage() {
+	public void hasTextWithNull() {
 		thrown.expect(IllegalArgumentException.class);
 		thrown.expectMessage("enigma");
 		Assert.hasText(null, "enigma");
@@ -245,21 +238,21 @@ public class AssertTests {
 
 	@Test
 	public void doesNotContainWithNullSearchString() {
-		Assert.doesNotContain(null, "rod");
+		Assert.doesNotContain(null, "rod", "enigma");
 	}
 
 	@Test
 	public void doesNotContainWithNullSubstring() {
-		Assert.doesNotContain("A cool chick's name is Brod.", null);
+		Assert.doesNotContain("A cool chick's name is Brod.", null, "enigma");
 	}
 
 	@Test
 	public void doesNotContainWithEmptySubstring() {
-		Assert.doesNotContain("A cool chick's name is Brod.", "");
+		Assert.doesNotContain("A cool chick's name is Brod.", "", "enigma");
 	}
 
 	@Test
-	public void doesNotContainWithNullSearchStringAndNullSubstringAndMessage() {
+	public void doesNotContainWithNullSearchStringAndNullSubstring() {
 		Assert.doesNotContain(null, null, "enigma");
 	}
 
@@ -299,12 +292,26 @@ public class AssertTests {
 
 	@Test
 	public void notEmptyArray() {
-		Assert.notEmpty(new String[] { "1234" });
+		Assert.notEmpty(new String[] {"1234"}, "enigma");
+	}
+
+	@Test
+	public void notEmptyArrayWithEmptyArray() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty(new String[] {}, "enigma");
+	}
+
+	@Test
+	public void notEmptyArrayWithNullArray() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty((Object[]) null, "enigma");
 	}
 
 	@Test
 	public void notEmptyArrayWithMessageSupplier() {
-		Assert.notEmpty(new String[] { "1234" }, () -> "enigma");
+		Assert.notEmpty(new String[] {"1234"}, () -> "enigma");
 	}
 
 	@Test
@@ -369,19 +376,21 @@ public class AssertTests {
 
 	@Test
 	public void notEmptyCollection() {
-		Assert.notEmpty(singletonList("foo"));
+		Assert.notEmpty(singletonList("foo"), "enigma");
 	}
 
 	@Test
 	public void notEmptyCollectionWithEmptyCollection() {
 		thrown.expect(IllegalArgumentException.class);
-		Assert.notEmpty(emptyList());
+		thrown.expectMessage("enigma");
+		Assert.notEmpty(emptyList(), "enigma");
 	}
 
 	@Test
 	public void notEmptyCollectionWithNullCollection() {
 		thrown.expect(IllegalArgumentException.class);
-		Assert.notEmpty((Collection) null);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty((Collection) null, "enigma");
 	}
 
 	@Test
@@ -412,19 +421,21 @@ public class AssertTests {
 
 	@Test
 	public void notEmptyMap() {
-		Assert.notEmpty(singletonMap("foo", "bar"));
+		Assert.notEmpty(singletonMap("foo", "bar"), "enigma");
 	}
 
 	@Test
 	public void notEmptyMapWithNullMap() {
 		thrown.expect(IllegalArgumentException.class);
-		Assert.notEmpty((Map) null);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty((Map) null, "enigma");
 	}
 
 	@Test
 	public void notEmptyMapWithEmptyMap() {
 		thrown.expect(IllegalArgumentException.class);
-		Assert.notEmpty(emptyMap());
+		thrown.expectMessage("enigma");
+		Assert.notEmpty(emptyMap(), "enigma");
 	}
 
 	@Test
@@ -455,21 +466,21 @@ public class AssertTests {
 
 	@Test
 	public void isInstanceOf() {
-		Assert.isInstanceOf(String.class, "foo");
+		Assert.isInstanceOf(String.class, "foo", "enigma");
 	}
 
 	@Test
 	public void isInstanceOfWithNullType() {
 		thrown.expect(IllegalArgumentException.class);
 		thrown.expectMessage("Type to check against must not be null");
-		Assert.isInstanceOf(null, "foo");
+		Assert.isInstanceOf(null, "foo", "enigma");
 	}
 
 	@Test
 	public void isInstanceOfWithNullInstance() {
 		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage("Object of class [null] must be an instance of class java.lang.String");
-		Assert.isInstanceOf(String.class, null);
+		thrown.expectMessage("enigma: null");
+		Assert.isInstanceOf(String.class, null, "enigma");
 	}
 
 	@Test
@@ -482,9 +493,8 @@ public class AssertTests {
 	@Test
 	public void isInstanceOfWithTypeMismatchAndCustomMessage() {
 		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage(
-			"Custom message. Object of class [java.lang.Long] must be an instance of class java.lang.String");
-		Assert.isInstanceOf(String.class, 42L, "Custom message.");
+		thrown.expectMessage("Custom message: java.lang.Long");
+		Assert.isInstanceOf(String.class, 42L, "Custom message");
 	}
 
 	@Test
@@ -502,8 +512,8 @@ public class AssertTests {
 	@Test
 	public void isInstanceOfWithNullInstanceAndMessageSupplier() {
 		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage("enigma: Object of class [null] must be an instance of class java.lang.String");
-		Assert.isInstanceOf(String.class, null, () -> "enigma:");
+		thrown.expectMessage("enigma: null");
+		Assert.isInstanceOf(String.class, null, () -> "enigma");
 	}
 
 	@Test
@@ -516,27 +526,27 @@ public class AssertTests {
 	@Test
 	public void isInstanceOfWithTypeMismatchAndMessageSupplier() {
 		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage("enigma: Object of class [java.lang.Long] must be an instance of class java.lang.String");
-		Assert.isInstanceOf(String.class, 42L, () -> "enigma:");
+		thrown.expectMessage("enigma: java.lang.Long");
+		Assert.isInstanceOf(String.class, 42L, () -> "enigma");
 	}
 
 	@Test
 	public void isAssignable() {
-		Assert.isAssignable(Number.class, Integer.class);
+		Assert.isAssignable(Number.class, Integer.class, "enigma");
 	}
 
 	@Test
 	public void isAssignableWithNullSupertype() {
 		thrown.expect(IllegalArgumentException.class);
 		thrown.expectMessage("Super type to check against must not be null");
-		Assert.isAssignable(null, Integer.class);
+		Assert.isAssignable(null, Integer.class, "enigma");
 	}
 
 	@Test
 	public void isAssignableWithNullSubtype() {
 		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage("null is not assignable to class java.lang.Integer");
-		Assert.isAssignable(Integer.class, null);
+		thrown.expectMessage("enigma: null");
+		Assert.isAssignable(Integer.class, null, "enigma");
 	}
 
 	@Test
@@ -549,8 +559,8 @@ public class AssertTests {
 	@Test
 	public void isAssignableWithTypeMismatchAndCustomMessage() {
 		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage("enigma: class java.lang.Integer is not assignable to class java.lang.String");
-		Assert.isAssignable(String.class, Integer.class, "enigma:");
+		thrown.expectMessage("enigma: class java.lang.Integer");
+		Assert.isAssignable(String.class, Integer.class, "enigma");
 	}
 
 	@Test
@@ -568,8 +578,8 @@ public class AssertTests {
 	@Test
 	public void isAssignableWithNullSubtypeAndMessageSupplier() {
 		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage("enigma: null is not assignable to class java.lang.Integer");
-		Assert.isAssignable(Integer.class, null, () -> "enigma:");
+		thrown.expectMessage("enigma: null");
+		Assert.isAssignable(Integer.class, null, () -> "enigma");
 	}
 
 	@Test
@@ -582,19 +592,20 @@ public class AssertTests {
 	@Test
 	public void isAssignableWithTypeMismatchAndMessageSupplier() {
 		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage("enigma: class java.lang.Integer is not assignable to class java.lang.String");
-		Assert.isAssignable(String.class, Integer.class, () -> "enigma:");
+		thrown.expectMessage("enigma: class java.lang.Integer");
+		Assert.isAssignable(String.class, Integer.class, () -> "enigma");
 	}
 
 	@Test
 	public void state() {
-		Assert.state(true);
+		Assert.state(true, "enigma");
 	}
 
 	@Test
 	public void stateWithFalseExpression() {
 		thrown.expect(IllegalStateException.class);
-		Assert.state(false);
+		thrown.expectMessage("enigma");
+		Assert.state(false, "enigma");
 	}
 
 	@Test
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpDec.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpDec.java
index 18026780422..206c382b20e 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpDec.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpDec.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,8 +43,8 @@ public class OpDec extends Operator {
 
 	public OpDec(int pos, boolean postfix, SpelNodeImpl... operands) {
 		super("--", pos, operands);
-		Assert.notEmpty(operands);
 		this.postfix = postfix;
+		Assert.notEmpty(operands, "Operands must not be empty");
 	}
 
 
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpInc.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpInc.java
index f7ec295e901..ab75f7b55a7 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpInc.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpInc.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,8 +43,8 @@ public class OpInc extends Operator {
 
 	public OpInc(int pos, boolean postfix, SpelNodeImpl... operands) {
 		super("++", pos, operands);
-		Assert.notEmpty(operands);
 		this.postfix = postfix;
+		Assert.notEmpty(operands, "Operands must not be empty");
 	}
 
 
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpPlus.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpPlus.java
index eeefe40ffb7..1fc99b21280 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpPlus.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpPlus.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,7 +51,7 @@ public class OpPlus extends Operator {
 
 	public OpPlus(int pos, SpelNodeImpl... operands) {
 		super("+", pos, operands);
-		Assert.notEmpty(operands);
+		Assert.notEmpty(operands, "Operands must not be empty");
 	}
 
 
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/Operator.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/Operator.java
index a47b9a103c7..f033519e5af 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/Operator.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/Operator.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,7 +51,7 @@ public abstract class Operator extends SpelNodeImpl {
 	protected String rightActualDescriptor;
 
 
-	public Operator(String payload,int pos,SpelNodeImpl... operands) {
+	public Operator(String payload, int pos, SpelNodeImpl... operands) {
 		super(pos, operands);
 		this.operatorName = payload;
 	}
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java b/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java
index 1257501d6c8..378da194861 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -79,6 +79,7 @@ import org.springframework.util.StringUtils;
  * Hand written SpEL parser. Instances are reusable but are not thread-safe.
  *
  * @author Andy Clement
+ * @author Juergen Hoeller
  * @author Phillip Webb
  * @since 3.0
  */
@@ -128,7 +129,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			if (moreTokens()) {
 				throw new SpelParseException(peekToken().startPos, SpelMessage.MORE_INPUT, toString(nextToken()));
 			}
-			Assert.isTrue(this.constructedNodes.isEmpty());
+			Assert.isTrue(this.constructedNodes.isEmpty(), "At least one node expected");
 			return new SpelExpression(expressionString, ast, this.configuration);
 		}
 		catch (InternalParseException ex) {
@@ -232,7 +233,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 				if (tk == TokenKind.EQ) {
 					return new OpEQ(pos, expr, rhExpr);
 				}
-				Assert.isTrue(tk == TokenKind.NE);
+				Assert.isTrue(tk == TokenKind.NE, "Not-equals token expected");
 				return new OpNE(pos, expr, rhExpr);
 			}
 
@@ -244,7 +245,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 				return new OperatorMatches(toPos(t), expr, rhExpr);
 			}
 
-			Assert.isTrue(tk == TokenKind.BETWEEN);
+			Assert.isTrue(tk == TokenKind.BETWEEN, "Between token expected");
 			return new OperatorBetween(toPos(t), expr, rhExpr);
 		}
 		return expr;
@@ -281,7 +282,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 				expr = new OpDivide(toPos(t), expr, rhExpr);
 			}
 			else {
-				Assert.isTrue(t.kind == TokenKind.MOD);
+				Assert.isTrue(t.kind == TokenKind.MOD, "Mod token expected");
 				expr = new OpModulus(toPos(t), expr, rhExpr);
 			}
 		}
@@ -298,7 +299,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			return new OperatorPower(toPos(t), expr, rhExpr);
 		}
 
-		if (expr != null && peekToken(TokenKind.INC,TokenKind.DEC)) {
+		if (expr != null && peekToken(TokenKind.INC, TokenKind.DEC)) {
 			Token t = nextToken();  //consume INC/DEC
 			if (t.getKind() == TokenKind.INC) {
 				return new OpInc(toPos(t), true, expr);
@@ -321,7 +322,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			if (t.kind == TokenKind.PLUS) {
 				return new OpPlus(toPos(t), expr);
 			}
-			Assert.isTrue(t.kind == TokenKind.MINUS);
+			Assert.isTrue(t.kind == TokenKind.MINUS, "Minus token expected");
 			return new OpMinus(toPos(t), expr);
 
 		}
@@ -356,7 +357,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 	// node : ((DOT dottedNode) | (SAFE_NAVI dottedNode) | nonDottedNode)+;
 	private boolean maybeEatNode() {
 		SpelNodeImpl expr = null;
-		if (peekToken(TokenKind.DOT,TokenKind.SAFE_NAVI)) {
+		if (peekToken(TokenKind.DOT, TokenKind.SAFE_NAVI)) {
 			expr = eatDottedNode();
 		}
 		else {
@@ -940,7 +941,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		return false;
 	}
 
-	private boolean peekToken(TokenKind possible1,TokenKind possible2) {
+	private boolean peekToken(TokenKind possible1, TokenKind possible2) {
 		if (!moreTokens()) {
 			return false;
 		}
@@ -948,12 +949,12 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		return (t.kind == possible1 || t.kind == possible2);
 	}
 
-	private boolean peekToken(TokenKind possible1,TokenKind possible2, TokenKind possible3) {
+	private boolean peekToken(TokenKind possible1, TokenKind possible2, TokenKind possible3) {
 		if (!moreTokens()) {
 			return false;
 		}
 		Token t = peekToken();
-		return t.kind == possible1 || t.kind == possible2 || t.kind == possible3;
+		return (t.kind == possible1 || t.kind == possible2 || t.kind == possible3);
 	}
 
 	private boolean peekIdentifierToken(String identifierString) {
@@ -961,7 +962,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			return false;
 		}
 		Token t = peekToken();
-		return t.kind == TokenKind.IDENTIFIER && t.stringValue().equalsIgnoreCase(identifierString);
+		return (t.kind == TokenKind.IDENTIFIER && t.stringValue().equalsIgnoreCase(identifierString));
 	}
 
 	private boolean peekSelectToken() {
@@ -969,8 +970,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			return false;
 		}
 		Token t = peekToken();
-		return t.kind == TokenKind.SELECT || t.kind == TokenKind.SELECT_FIRST
-				|| t.kind == TokenKind.SELECT_LAST;
+		return (t.kind == TokenKind.SELECT || t.kind == TokenKind.SELECT_FIRST || t.kind == TokenKind.SELECT_LAST);
 	}
 
 	private boolean moreTokens() {
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java b/spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java
index ce227875ac9..a4c8b8ab5b8 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,7 +23,6 @@ import java.util.List;
 import org.springframework.expression.spel.InternalParseException;
 import org.springframework.expression.spel.SpelMessage;
 import org.springframework.expression.spel.SpelParseException;
-import org.springframework.util.Assert;
 
 /**
  * Lex some input data into a stream of tokens that can then be parsed.
@@ -522,9 +521,9 @@ class Tokenizer {
 	 * Check if this might be a two character token.
 	 */
 	private boolean isTwoCharToken(TokenKind kind) {
-		Assert.isTrue(kind.tokenChars.length == 2);
-		Assert.isTrue(this.toProcess[this.pos] == kind.tokenChars[0]);
-		return this.toProcess[this.pos + 1] == kind.tokenChars[1];
+		return (kind.tokenChars.length == 2 &&
+				this.toProcess[this.pos] == kind.tokenChars[0] &&
+				this.toProcess[this.pos + 1] == kind.tokenChars[1]);
 	}
 
 	/**
diff --git a/spring-jdbc/src/main/java/org/springframework/jdbc/core/ParameterDisposer.java b/spring-jdbc/src/main/java/org/springframework/jdbc/core/ParameterDisposer.java
index 6687ec16884..cfa205b2679 100644
--- a/spring-jdbc/src/main/java/org/springframework/jdbc/core/ParameterDisposer.java
+++ b/spring-jdbc/src/main/java/org/springframework/jdbc/core/ParameterDisposer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2005 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,11 +18,11 @@ package org.springframework.jdbc.core;
 
 /**
  * Interface to be implemented by objects that can close resources
- * allocated by parameters like SqlLobValues.
+ * allocated by parameters like {@code SqlLobValue} objects.
  *
- * 
Typically implemented by PreparedStatementCreators and
- * PreparedStatementSetters that support DisposableSqlTypeValue
- * objects (e.g. SqlLobValue) as parameters.
+ * 
Typically implemented by {@code PreparedStatementCreators} and
+ * {@code PreparedStatementSetters} that support {@link DisposableSqlTypeValue}
+ * objects (e.g. {@code SqlLobValue}) as parameters.
  *
  * @author Thomas Risberg
  * @author Juergen Hoeller
@@ -38,9 +38,9 @@ public interface ParameterDisposer {
 	 * Close the resources allocated by parameters that the implementing
 	 * object holds, for example in case of a DisposableSqlTypeValue
 	 * (like a SqlLobValue).
-	 * @see DisposableSqlTypeValue#cleanup
-	 * @see org.springframework.jdbc.core.support.SqlLobValue#cleanup
+	 * @see DisposableSqlTypeValue#cleanup()
+	 * @see org.springframework.jdbc.core.support.SqlLobValue#cleanup()
 	 */
-	public void cleanupParameters();
+	void cleanupParameters();
 
 }
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandlerComposite.java b/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandlerComposite.java
index bc2d01d5bcb..99ff814643d 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandlerComposite.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandlerComposite.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -94,7 +94,9 @@ public class HandlerMethodReturnValueHandlerComposite implements AsyncHandlerMet
 			throws Exception {
 
 		HandlerMethodReturnValueHandler handler = getReturnValueHandler(returnType);
-		Assert.notNull(handler, "No handler for return value type [" + returnType.getParameterType().getName() + "]");
+		if (handler == null) {
+			throw new IllegalStateException("No handler for return value type: " + returnType.getParameterType());
+		}
 		if (logger.isTraceEnabled()) {
 			logger.trace("Processing return value with " + handler);
 		}
@@ -104,14 +106,15 @@ public class HandlerMethodReturnValueHandlerComposite implements AsyncHandlerMet
 	@Override
 	public boolean isAsyncReturnValue(Object returnValue, MethodParameter returnType) {
 		HandlerMethodReturnValueHandler handler = getReturnValueHandler(returnType);
-		return (handler != null && handler instanceof AsyncHandlerMethodReturnValueHandler &&
+		return (handler instanceof AsyncHandlerMethodReturnValueHandler &&
 				((AsyncHandlerMethodReturnValueHandler) handler).isAsyncReturnValue(returnValue, returnType));
 	}
 
 	@Override
 	public ListenableFuture toListenableFuture(Object returnValue, MethodParameter returnType) {
 		HandlerMethodReturnValueHandler handler = getReturnValueHandler(returnType);
-		Assert.isTrue(handler != null && handler instanceof AsyncHandlerMethodReturnValueHandler);
+		Assert.state(handler instanceof AsyncHandlerMethodReturnValueHandler,
+				"AsyncHandlerMethodReturnValueHandler required");
 		return ((AsyncHandlerMethodReturnValueHandler) handler).toListenableFuture(returnValue, returnType);
 	}
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/SimpMessagingTemplate.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/SimpMessagingTemplate.java
index 493f1224b21..0088adb7d84 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/SimpMessagingTemplate.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/SimpMessagingTemplate.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,10 +58,10 @@ public class SimpMessagingTemplate extends AbstractMessageSendingTemplate message) {
-		Assert.notNull(message, "'message' is required");
+		Assert.notNull(message, "Message is required");
 		String destination = SimpMessageHeaderAccessor.getDestination(message.getHeaders());
 		if (destination != null) {
 			sendInternal(message);
@@ -178,7 +178,7 @@ public class SimpMessagingTemplate extends AbstractMessageSendingTemplate message) {
 		String destination = SimpMessageHeaderAccessor.getDestination(message.getHeaders());
-		Assert.notNull(destination);
+		Assert.notNull(destination, "Destination header required");
 
 		long timeout = this.sendTimeout;
 		boolean sent = (timeout >= 0 ? this.messageChannel.send(message, timeout) : this.messageChannel.send(message));
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java
index 83ef7bf4856..7d52150ea89 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -480,7 +480,7 @@ public class SimpAnnotationMethodMessageHandler extends AbstractMethodMessageHan
 			Map vars = getPathMatcher().extractUriTemplateVariables(pattern, lookupDestination);
 			if (!CollectionUtils.isEmpty(vars)) {
 				MessageHeaderAccessor mha = MessageHeaderAccessor.getAccessor(message, MessageHeaderAccessor.class);
-				Assert.state(mha != null && mha.isMutable());
+				Assert.state(mha != null && mha.isMutable(), "Mutable MessageHeaderAccessor required");
 				mha.setHeader(DestinationVariableMethodArgumentResolver.DESTINATION_TEMPLATE_VARIABLES_HEADER, vars);
 			}
 		}
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandler.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandler.java
index 2c9c8f52e6b..290ee6dffe7 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandler.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package org.springframework.messaging.simp.broker;
 
 import java.security.Principal;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -174,7 +175,9 @@ public class SimpleBrokerMessageHandler extends AbstractBrokerMessageHandler {
 	 * @since 4.2
 	 */
 	public void setHeartbeatValue(long[] heartbeat) {
-		Assert.notNull(heartbeat);
+		if (heartbeat == null || heartbeat.length != 2 || heartbeat[0] < 0 || heartbeat[1] < 0) {
+			throw new IllegalArgumentException("Invalid heart-beat: " + Arrays.toString(heartbeat));
+		}
 		this.heartbeatValue = heartbeat;
 	}
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractMessageBrokerConfiguration.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractMessageBrokerConfiguration.java
index bace1fc4f73..95c483c66d2 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractMessageBrokerConfiguration.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractMessageBrokerConfiguration.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -317,14 +317,14 @@ public abstract class AbstractMessageBrokerConfiguration implements ApplicationC
 			return new NoOpMessageHandler();
 		}
 		SimpUserRegistry userRegistry = userRegistry();
-		Assert.isInstanceOf(MultiServerUserRegistry.class, userRegistry);
+		Assert.isInstanceOf(MultiServerUserRegistry.class, userRegistry, "MultiServerUserRegistry required");
 		return new UserRegistryMessageHandler((MultiServerUserRegistry) userRegistry,
 				brokerMessagingTemplate(), getBrokerRegistry().getUserRegistryBroadcast(),
 				messageBrokerTaskScheduler());
 	}
 
 	// Expose alias for 4.1 compatibility
-	@Bean(name={"messageBrokerTaskScheduler", "messageBrokerSockJsTaskScheduler"})
+	@Bean(name = {"messageBrokerTaskScheduler", "messageBrokerSockJsTaskScheduler"})
 	public ThreadPoolTaskScheduler messageBrokerTaskScheduler() {
 		ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
 		scheduler.setThreadNamePrefix("MessageBroker-");
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/MessageBrokerRegistry.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/MessageBrokerRegistry.java
index 3c8dd759d22..5267b0ffffa 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/MessageBrokerRegistry.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/MessageBrokerRegistry.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,8 +55,8 @@ public class MessageBrokerRegistry {
 
 
 	public MessageBrokerRegistry(SubscribableChannel clientInboundChannel, MessageChannel clientOutboundChannel) {
-		Assert.notNull(clientInboundChannel);
-		Assert.notNull(clientOutboundChannel);
+		Assert.notNull(clientInboundChannel, "Inbound channel must not be null");
+		Assert.notNull(clientOutboundChannel, "Outbound channel must not be null");
 		this.clientInboundChannel = clientInboundChannel;
 		this.clientOutboundChannel = clientOutboundChannel;
 	}
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java
index ddba2d794b8..7cb3b6557c2 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -175,7 +175,7 @@ public class DefaultStompSession implements ConnectionHandlingStompSession {
 	 * 
By default set to 15,000 (15 seconds).
 	 */
 	public void setReceiptTimeLimit(long receiptTimeLimit) {
-		Assert.isTrue(receiptTimeLimit > 0);
+		Assert.isTrue(receiptTimeLimit > 0, "Receipt time limit must be larger than zero");
 		this.receiptTimeLimit = receiptTimeLimit;
 	}
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java
index 708f277b9cc..ea51cb93393 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -126,7 +126,7 @@ public abstract class StompClientSupport {
 	 * 
By default set to 15,000 (15 seconds).
 	 */
 	public void setReceiptTimeLimit(long receiptTimeLimit) {
-		Assert.isTrue(receiptTimeLimit > 0);
+		Assert.isTrue(receiptTimeLimit > 0, "Receipt time limit must be larger than zero");
 		this.receiptTimeLimit = receiptTimeLimit;
 	}
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/tcp/reactor/AbstractMonoToListenableFutureAdapter.java b/spring-messaging/src/main/java/org/springframework/messaging/tcp/reactor/AbstractMonoToListenableFutureAdapter.java
index 8b6cf5bcf74..cfd259b5d3a 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/tcp/reactor/AbstractMonoToListenableFutureAdapter.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/tcp/reactor/AbstractMonoToListenableFutureAdapter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -48,7 +48,7 @@ abstract class AbstractMonoToListenableFutureAdapter implements Listenable
 
 
 	protected AbstractMonoToListenableFutureAdapter(Mono mono) {
-		Assert.notNull(mono, "'mono' must not be null");
+		Assert.notNull(mono, "Mono must not be null");
 		this.monoProcessor = mono
 				.doOnSuccess(result -> {
 					T adapted;
@@ -73,10 +73,8 @@ abstract class AbstractMonoToListenableFutureAdapter implements Listenable
 	}
 
 	@Override
-	public T get(long timeout, TimeUnit unit)
-			throws InterruptedException, ExecutionException, TimeoutException {
-
-		Assert.notNull(unit);
+	public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
+		Assert.notNull(unit, "TimeUnit must not be null");
 		Duration duration = Duration.ofMillis(TimeUnit.MILLISECONDS.convert(timeout, unit));
 		S result = this.monoProcessor.block(duration);
 		return adapt(result);
@@ -112,6 +110,7 @@ abstract class AbstractMonoToListenableFutureAdapter implements Listenable
 		this.registry.addFailureCallback(failureCallback);
 	}
 
+
 	protected abstract T adapt(S result);
 
 }
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyTcpStompClientTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyTcpStompClientTests.java
index bdfe762af13..df9ea9a7b5c 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyTcpStompClientTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyTcpStompClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -159,7 +159,7 @@ public class ReactorNettyTcpStompClientTests {
 		private final List received = new ArrayList<>();
 
 		public ConsumingHandler(String... topics) {
-			Assert.notEmpty(topics);
+			Assert.notEmpty(topics, "Topics must not be empty");
 			this.topics = Arrays.asList(topics);
 			this.subscriptionLatch = new CountDownLatch(this.topics.size());
 		}
@@ -168,7 +168,6 @@ public class ReactorNettyTcpStompClientTests {
 			return this.received;
 		}
 
-
 		@Override
 		public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
 			for (String topic : this.topics) {
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerIntegrationTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerIntegrationTests.java
index feba05c29f0..2fa8335ae0a 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerIntegrationTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -399,7 +399,6 @@ public class StompBrokerRelayMessageHandlerIntegrationTests {
 		}
 
 		public static MessageExchangeBuilder disconnectWithReceipt(String sessionId, String receiptId) {
-
 			StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.DISCONNECT);
 			headers.setSessionId(sessionId);
 			headers.setReceipt(receiptId);
@@ -411,7 +410,7 @@ public class StompBrokerRelayMessageHandlerIntegrationTests {
 		}
 
 		public MessageExchangeBuilder andExpectMessage(String sessionId, String subscriptionId) {
-			Assert.isTrue(SimpMessageType.MESSAGE.equals(headers.getMessageType()));
+			Assert.state(SimpMessageType.MESSAGE.equals(this.headers.getMessageType()), "MESSAGE type expected");
 			String destination = this.headers.getDestination();
 			Object payload = this.message.getPayload();
 			this.expected.add(new StompMessageFrameMessageMatcher(sessionId, subscriptionId, destination, payload));
@@ -420,7 +419,7 @@ public class StompBrokerRelayMessageHandlerIntegrationTests {
 
 		public MessageExchangeBuilder andExpectError() {
 			String sessionId = this.headers.getSessionId();
-			Assert.notNull(sessionId, "No sessionId to match the ERROR frame to");
+			Assert.state(sessionId != null, "No sessionId to match the ERROR frame to");
 			return andExpectError(sessionId);
 		}
 
diff --git a/spring-orm/src/main/java/org/springframework/orm/hibernate5/SessionFactoryUtils.java b/spring-orm/src/main/java/org/springframework/orm/hibernate5/SessionFactoryUtils.java
index 7f3d2e28a78..fafa3f6b784 100644
--- a/spring-orm/src/main/java/org/springframework/orm/hibernate5/SessionFactoryUtils.java
+++ b/spring-orm/src/main/java/org/springframework/orm/hibernate5/SessionFactoryUtils.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -110,7 +110,7 @@ public abstract class SessionFactoryUtils {
 			}
 		}
 		// Check that it is the Hibernate FlushMode type, not JPA's...
-		Assert.state(FlushMode.class == getFlushMode.getReturnType());
+		Assert.state(FlushMode.class == getFlushMode.getReturnType(), "Could not find Hibernate getFlushMode method");
 	}
 
 
diff --git a/spring-orm/src/main/java/org/springframework/orm/jpa/AbstractEntityManagerFactoryBean.java b/spring-orm/src/main/java/org/springframework/orm/jpa/AbstractEntityManagerFactoryBean.java
index 64648b559f2..4a898b37108 100644
--- a/spring-orm/src/main/java/org/springframework/orm/jpa/AbstractEntityManagerFactoryBean.java
+++ b/spring-orm/src/main/java/org/springframework/orm/jpa/AbstractEntityManagerFactoryBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -135,7 +135,6 @@ public abstract class AbstractEntityManagerFactoryBean implements
 	 * @see javax.persistence.Persistence
 	 */
 	public void setPersistenceProviderClass(Class persistenceProviderClass) {
-		Assert.isAssignable(PersistenceProvider.class, persistenceProviderClass);
 		this.persistenceProvider = BeanUtils.instantiateClass(persistenceProviderClass);
 	}
 
@@ -217,7 +216,6 @@ public abstract class AbstractEntityManagerFactoryBean implements
 	 * @see JpaVendorAdapter#getEntityManagerFactoryInterface()
 	 */
 	public void setEntityManagerFactoryInterface(Class emfInterface) {
-		Assert.isAssignable(EntityManagerFactory.class, emfInterface);
 		this.entityManagerFactoryInterface = emfInterface;
 	}
 
@@ -231,7 +229,6 @@ public abstract class AbstractEntityManagerFactoryBean implements
 	 * @see EntityManagerFactoryInfo#getEntityManagerInterface()
 	 */
 	public void setEntityManagerInterface(Class emInterface) {
-		Assert.isAssignable(EntityManager.class, emInterface);
 		this.entityManagerInterface = emInterface;
 	}
 
diff --git a/spring-orm/src/main/java/org/springframework/orm/jpa/support/SharedEntityManagerBean.java b/spring-orm/src/main/java/org/springframework/orm/jpa/support/SharedEntityManagerBean.java
index c6595279de5..4c5b44592d0 100644
--- a/spring-orm/src/main/java/org/springframework/orm/jpa/support/SharedEntityManagerBean.java
+++ b/spring-orm/src/main/java/org/springframework/orm/jpa/support/SharedEntityManagerBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -68,7 +68,6 @@ public class SharedEntityManagerBean extends EntityManagerFactoryAccessor
 	 */
 	public void setEntityManagerInterface(Class entityManagerInterface) {
 		Assert.notNull(entityManagerInterface, "'entityManagerInterface' must not be null");
-		Assert.isAssignable(EntityManager.class, entityManagerInterface);
 		this.entityManagerInterface = entityManagerInterface;
 	}
 
diff --git a/spring-orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaDialect.java b/spring-orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaDialect.java
index 8428f094715..93458e7bdd3 100644
--- a/spring-orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaDialect.java
+++ b/spring-orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaDialect.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -100,7 +100,7 @@ public class HibernateJpaDialect extends DefaultJpaDialect {
 			}
 		}
 		// Check that it is the Hibernate FlushMode type, not JPA's...
-		Assert.state(FlushMode.class == getFlushMode.getReturnType());
+		Assert.state(FlushMode.class == getFlushMode.getReturnType(), "Could not find Hibernate getFlushMode method");
 	}
 
 
diff --git a/spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java b/spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java
index 740dfe535e5..c5f09841f70 100644
--- a/spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java
+++ b/spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -79,7 +79,6 @@ import org.springframework.oxm.UncategorizedMappingException;
 import org.springframework.oxm.UnmarshallingFailureException;
 import org.springframework.oxm.XmlMappingException;
 import org.springframework.oxm.support.AbstractMarshaller;
-import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
@@ -114,7 +113,7 @@ import org.springframework.util.xml.StaxUtils;
  * @author Juergen Hoeller
  * @since 3.0
  */
-public class XStreamMarshaller extends AbstractMarshaller implements InitializingBean, BeanClassLoaderAware {
+public class XStreamMarshaller extends AbstractMarshaller implements BeanClassLoaderAware, InitializingBean {
 
 	/**
 	 * The default encoding used for stream access: UTF-8.
@@ -130,7 +129,7 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 
 	private Mapper mapper;
 
-	private Class[] mapperWrappers;
+	private Class[] mapperWrappers;
 
 	private ConverterLookup converterLookup = new DefaultConverterLookup();
 
@@ -210,7 +209,8 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 	 * of type {@link Mapper} or {@link MapperWrapper}.
 	 * @since 4.0
 	 */
-	public void setMapperWrappers(Class... mapperWrappers) {
+	@SuppressWarnings("unchecked")
+	public void setMapperWrappers(Class... mapperWrappers) {
 		this.mapperWrappers = mapperWrappers;
 	}
 
@@ -413,9 +413,8 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 			protected MapperWrapper wrapMapper(MapperWrapper next) {
 				MapperWrapper mapperToWrap = next;
 				if (mapperWrappers != null) {
-					for (Class mapperWrapper : mapperWrappers) {
-						Assert.isAssignable(MapperWrapper.class, mapperWrapper);
-						Constructor ctor;
+					for (Class mapperWrapper : mapperWrappers) {
+						Constructor ctor;
 						try {
 							ctor = mapperWrapper.getConstructor(Mapper.class);
 						}
@@ -428,9 +427,9 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 							}
 						}
 						try {
-							mapperToWrap = (MapperWrapper) ctor.newInstance(mapperToWrap);
+							mapperToWrap = ctor.newInstance(mapperToWrap);
 						}
-						catch (Exception ex) {
+						catch (Throwable ex) {
 							throw new IllegalStateException("Failed to construct MapperWrapper: " + mapperWrapper);
 						}
 					}
diff --git a/spring-test/src/main/java/org/springframework/mock/web/MockAsyncContext.java b/spring-test/src/main/java/org/springframework/mock/web/MockAsyncContext.java
index f8d6e4cddca..c13ca8ffa8c 100644
--- a/spring-test/src/main/java/org/springframework/mock/web/MockAsyncContext.java
+++ b/spring-test/src/main/java/org/springframework/mock/web/MockAsyncContext.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -61,7 +61,7 @@ public class MockAsyncContext implements AsyncContext {
 
 
 	public void addDispatchHandler(Runnable handler) {
-		Assert.notNull(handler);
+		Assert.notNull(handler, "Dispatch handler must not be null");
 		this.dispatchHandlers.add(handler);
 	}
 
@@ -77,7 +77,7 @@ public class MockAsyncContext implements AsyncContext {
 
 	@Override
 	public boolean hasOriginalRequestAndResponse() {
-		return (this.request instanceof MockHttpServletRequest) && (this.response instanceof MockHttpServletResponse);
+		return (this.request instanceof MockHttpServletRequest && this.response instanceof MockHttpServletResponse);
 	}
 
 	@Override
diff --git a/spring-test/src/main/java/org/springframework/mock/web/MockPageContext.java b/spring-test/src/main/java/org/springframework/mock/web/MockPageContext.java
index 02dc7465e46..667741742cf 100644
--- a/spring-test/src/main/java/org/springframework/mock/web/MockPageContext.java
+++ b/spring-test/src/main/java/org/springframework/mock/web/MockPageContext.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -356,12 +356,12 @@ public class MockPageContext extends PageContext {
 	}
 
 	public byte[] getContentAsByteArray() {
-		Assert.isTrue(this.response instanceof MockHttpServletResponse);
+		Assert.state(this.response instanceof MockHttpServletResponse, "MockHttpServletResponse required");
 		return ((MockHttpServletResponse) this.response).getContentAsByteArray();
 	}
 
 	public String getContentAsString() throws UnsupportedEncodingException {
-		Assert.isTrue(this.response instanceof MockHttpServletResponse);
+		Assert.state(this.response instanceof MockHttpServletResponse, "MockHttpServletResponse required");
 		return ((MockHttpServletResponse) this.response).getContentAsString();
 	}
 
diff --git a/spring-test/src/main/java/org/springframework/test/web/client/SimpleRequestExpectationManager.java b/spring-test/src/main/java/org/springframework/test/web/client/SimpleRequestExpectationManager.java
index dbcf3852de4..89d91f1e62a 100644
--- a/spring-test/src/main/java/org/springframework/test/web/client/SimpleRequestExpectationManager.java
+++ b/spring-test/src/main/java/org/springframework/test/web/client/SimpleRequestExpectationManager.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,7 +43,7 @@ public class SimpleRequestExpectationManager extends AbstractRequestExpectationM
 
 	@Override
 	protected void afterExpectationsDeclared() {
-		Assert.state(this.expectationIterator == null);
+		Assert.state(this.expectationIterator == null, "Expectations already declared");
 		this.expectationIterator = getExpectations().iterator();
 	}
 
diff --git a/spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/FrameworkExtensionTests.java b/spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/FrameworkExtensionTests.java
index f194c41a45b..62a9ad65883 100644
--- a/spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/FrameworkExtensionTests.java
+++ b/spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/FrameworkExtensionTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,10 +41,10 @@ import static org.springframework.test.web.servlet.setup.MockMvcBuilders.*;
 /**
  * Demonstrates use of SPI extension points:
  * 
    
- * 	
  •  {@link org.springframework.test.web.servlet.request.RequestPostProcessor}
- * 	for extending request building with custom methods.
- * 	
  •  {@link org.springframework.test.web.servlet.setup.MockMvcConfigurer
- * 	MockMvcConfigurer} for extending MockMvc building with some automatic setup.
+ * 
  •  {@link org.springframework.test.web.servlet.request.RequestPostProcessor}
+ * for extending request building with custom methods.
+ * 
  •  {@link org.springframework.test.web.servlet.setup.MockMvcConfigurer
+ * MockMvcConfigurer} for extending MockMvc building with some automatic setup.
  * 

  *
  * @author Rossen Stoyanchev
@@ -106,6 +106,7 @@ public class FrameworkExtensionTests {
 		}
 	}
 
+
 	/**
 	 * Test {@code MockMvcConfigurer}.
 	 */
@@ -126,6 +127,7 @@ public class FrameworkExtensionTests {
 		}
 	}
 
+
 	@Controller
 	@RequestMapping("/")
 	private static class SampleController {
@@ -133,16 +135,16 @@ public class FrameworkExtensionTests {
 		@RequestMapping(headers = "Foo")
 		@ResponseBody
 		public String handleFoo(Principal principal) {
-			Assert.isTrue(principal != null);
+			Assert.notNull(principal, "Principal must not be null");
 			return "Foo";
 		}
 
 		@RequestMapping(headers = "Bar")
 		@ResponseBody
 		public String handleBar(Principal principal) {
-			Assert.isTrue(principal != null);
+			Assert.notNull(principal, "Principal must not be null");
 			return "Bar";
 		}
 	}
 
-}
\ No newline at end of file
+}
diff --git a/spring-tx/src/main/java/org/springframework/jca/support/ResourceAdapterFactoryBean.java b/spring-tx/src/main/java/org/springframework/jca/support/ResourceAdapterFactoryBean.java
index 7e7ff1eda5d..d4b7d3084e5 100644
--- a/spring-tx/src/main/java/org/springframework/jca/support/ResourceAdapterFactoryBean.java
+++ b/spring-tx/src/main/java/org/springframework/jca/support/ResourceAdapterFactoryBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,7 +26,6 @@ import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
-import org.springframework.util.Assert;
 
 /**
  * {@link org.springframework.beans.factory.FactoryBean} that bootstraps
@@ -66,9 +65,8 @@ public class ResourceAdapterFactoryBean implements FactoryBean,
 	 * through the "resourceAdapter" property.
 	 * @see #setResourceAdapter
 	 */
-	public void setResourceAdapterClass(Class resourceAdapterClass) {
-		Assert.isAssignable(ResourceAdapter.class, resourceAdapterClass);
-		this.resourceAdapter = (ResourceAdapter) BeanUtils.instantiateClass(resourceAdapterClass);
+	public void setResourceAdapterClass(Class resourceAdapterClass) {
+		this.resourceAdapter = BeanUtils.instantiateClass(resourceAdapterClass);
 	}
 
 	/**
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/config/UrlBasedViewResolverRegistration.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/config/UrlBasedViewResolverRegistration.java
index 3da533a38dc..553bc9503ab 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/config/UrlBasedViewResolverRegistration.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/config/UrlBasedViewResolverRegistration.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.web.reactive.config;
 
 import org.springframework.util.Assert;
@@ -30,7 +31,7 @@ public class UrlBasedViewResolverRegistration {
 
 
 	public UrlBasedViewResolverRegistration(UrlBasedViewResolver viewResolver) {
-		Assert.notNull(viewResolver);
+		Assert.notNull(viewResolver, "ViewResolver must not be null");
 		this.viewResolver = viewResolver;
 	}
 
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/config/ViewResolverRegistry.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/config/ViewResolverRegistry.java
index 9c083e2d6d5..a6e1a4558bb 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/config/ViewResolverRegistry.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/config/ViewResolverRegistry.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.web.reactive.config;
 
 import java.util.ArrayList;
@@ -32,7 +33,6 @@ import org.springframework.web.reactive.result.view.ViewResolver;
 import org.springframework.web.reactive.result.view.freemarker.FreeMarkerConfigurer;
 import org.springframework.web.reactive.result.view.freemarker.FreeMarkerViewResolver;
 
-
 /**
  * Assist with the configuration of a chain of {@link ViewResolver}'s supporting
  * different template mechanisms.
@@ -46,17 +46,17 @@ import org.springframework.web.reactive.result.view.freemarker.FreeMarkerViewRes
  */
 public class ViewResolverRegistry {
 
+	private final ApplicationContext applicationContext;
+
 	private final List viewResolvers = new ArrayList<>(4);
 
 	private final List defaultViews = new ArrayList<>(4);
 
 	private Integer order;
 
-	private final ApplicationContext applicationContext;
-
 
 	public ViewResolverRegistry(ApplicationContext applicationContext) {
-		Assert.notNull(applicationContext);
+		Assert.notNull(applicationContext, "ApplicationContext must not be null");
 		this.applicationContext = applicationContext;
 	}
 
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/handler/AbstractHandlerMapping.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/handler/AbstractHandlerMapping.java
index 7de183cc0b5..55893778d84 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/handler/AbstractHandlerMapping.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/handler/AbstractHandlerMapping.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,10 +41,13 @@ import org.springframework.web.server.support.HttpRequestPathHelper;
  * implementations.
  *
  * @author Rossen Stoyanchev
+ * @author Juergen Hoeller
  * @since 5.0
  */
-public abstract class AbstractHandlerMapping extends ApplicationObjectSupport
-		implements HandlerMapping, Ordered {
+public abstract class AbstractHandlerMapping extends ApplicationObjectSupport implements HandlerMapping, Ordered {
+
+	private static final WebHandler REQUEST_HANDLED_HANDLER = exchange -> Mono.empty();
+
 
 	private int order = Integer.MAX_VALUE;  // default: same as non-Ordered
 
@@ -158,7 +161,6 @@ public abstract class AbstractHandlerMapping extends ApplicationObjectSupport
 				CorsConfiguration configA = this.globalCorsConfigSource.getCorsConfiguration(exchange);
 				CorsConfiguration configB = getCorsConfiguration(handler, exchange);
 				CorsConfiguration config = (configA != null ? configA.combine(configB) : configB);
-
 				if (!getCorsProcessor().processRequest(config, exchange) ||
 						CorsUtils.isPreFlightRequest(exchange.getRequest())) {
 					return REQUEST_HANDLED_HANDLER;
@@ -171,13 +173,11 @@ public abstract class AbstractHandlerMapping extends ApplicationObjectSupport
 	/**
 	 * Look up a handler for the given request, returning an empty {@code Mono}
 	 * if no specific one is found. This method is called by {@link #getHandler}.
-	 *
 	 * 
On CORS pre-flight requests this method should return a match not for
 	 * the pre-flight request but for the expected actual request based on the URL
 	 * path, the HTTP methods from the "Access-Control-Request-Method" header, and
 	 * the headers from the "Access-Control-Request-Headers" header thus allowing
 	 * the CORS configuration to be obtained via {@link #getCorsConfigurations},
-	 *
 	 * @param exchange current exchange
 	 * @return {@code Mono} for the matching handler, if any
 	 */
@@ -185,18 +185,15 @@ public abstract class AbstractHandlerMapping extends ApplicationObjectSupport
 
 	/**
 	 * Retrieve the CORS configuration for the given handler.
-	 * @param handler the handler to check (never {@code null}).
+	 * @param handler the handler to check (never {@code null})
 	 * @param exchange the current exchange
-	 * @return the CORS configuration for the handler or {@code null}.
+	 * @return the CORS configuration for the handler, or {@code null} if none
 	 */
 	protected CorsConfiguration getCorsConfiguration(Object handler, ServerWebExchange exchange) {
-		if (handler != null && handler instanceof CorsConfigurationSource) {
+		if (handler instanceof CorsConfigurationSource) {
 			return ((CorsConfigurationSource) handler).getCorsConfiguration(exchange);
 		}
 		return null;
 	}
 
-
-	private static final WebHandler REQUEST_HANDLED_HANDLER = exchange -> Mono.empty();
-
-}
\ No newline at end of file
+}
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/handler/AbstractUrlHandlerMapping.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/handler/AbstractUrlHandlerMapping.java
index a937fb8a7b1..57122fd8aae 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/handler/AbstractUrlHandlerMapping.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/handler/AbstractUrlHandlerMapping.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,6 +44,7 @@ import org.springframework.web.server.ServerWebExchange;
  * path pattern that matches the current request path.
  *
  * @author Rossen Stoyanchev
+ * @author Juergen Hoeller
  * @since 5.0
  */
 public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping {
@@ -137,6 +138,7 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping {
 		if (handler != null) {
 			return handleMatch(handler, urlPath, urlPath, exchange);
 		}
+
 		// Pattern match?
 		List matches = new ArrayList<>();
 		for (String pattern : this.handlerMap.keySet()) {
@@ -149,6 +151,7 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping {
 				}
 			}
 		}
+
 		String bestMatch = null;
 		Comparator comparator = getPathMatcher().getPatternComparator(urlPath);
 		if (!matches.isEmpty()) {
@@ -161,12 +164,18 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping {
 		if (bestMatch != null) {
 			handler = this.handlerMap.get(bestMatch);
 			if (handler == null) {
-				Assert.isTrue(bestMatch.endsWith("/"));
-				handler = this.handlerMap.get(bestMatch.substring(0, bestMatch.length() - 1));
+				if (bestMatch.endsWith("/")) {
+					handler = this.handlerMap.get(bestMatch.substring(0, bestMatch.length() - 1));
+				}
+				if (handler == null) {
+					throw new IllegalStateException(
+							"Could not find handler for best pattern match [" + bestMatch + "]");
+				}
 			}
 			String pathWithinMapping = getPathMatcher().extractPathWithinPattern(bestMatch, urlPath);
 			return handleMatch(handler, bestMatch, pathWithinMapping, exchange);
 		}
+
 		// No handler found...
 		return null;
 	}
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/AbstractHandlerMethodMapping.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/AbstractHandlerMethodMapping.java
index 28694baab4a..325fd55acd2 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/AbstractHandlerMethodMapping.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/AbstractHandlerMethodMapping.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -52,11 +52,10 @@ import org.springframework.web.server.ServerWebExchange;
  * 
For each registered handler method, a unique mapping is maintained with
  * subclasses defining the details of the mapping type {@code }.
  *
- * @param  The mapping for a {@link HandlerMethod} containing the conditions
- * needed to match the handler method to incoming request.
- *
  * @author Rossen Stoyanchev
  * @since 5.0
+ * @param  The mapping for a {@link HandlerMethod} containing the conditions
+ * needed to match the handler method to incoming request.
  */
 public abstract class AbstractHandlerMethodMapping extends AbstractHandlerMapping implements InitializingBean {
 
@@ -570,10 +569,9 @@ public abstract class AbstractHandlerMethodMapping extends AbstractHandlerMap
 
 		private final List directUrls;
 
-
 		public MappingRegistration(T mapping, HandlerMethod handlerMethod, List directUrls) {
-			Assert.notNull(mapping);
-			Assert.notNull(handlerMethod);
+			Assert.notNull(mapping, "Mapping must not be null");
+			Assert.notNull(handlerMethod, "HandlerMethod must not be null");
 			this.mapping = mapping;
 			this.handlerMethod = handlerMethod;
 			this.directUrls = (directUrls != null ? directUrls : Collections.emptyList());
@@ -629,10 +627,11 @@ public abstract class AbstractHandlerMethodMapping extends AbstractHandlerMap
 		}
 	}
 
+
 	private static class PreFlightAmbiguousMatchHandler {
 
 		public void handle() {
-			throw new UnsupportedOperationException("not implemented");
+			throw new UnsupportedOperationException("Not implemented");
 		}
 	}
 
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/SyncInvocableHandlerMethod.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/SyncInvocableHandlerMethod.java
index ddecf58e125..cc020ddf170 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/SyncInvocableHandlerMethod.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/SyncInvocableHandlerMethod.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,7 +55,7 @@ public class SyncInvocableHandlerMethod extends InvocableHandlerMethod {
 	public void setArgumentResolvers(List resolvers) {
 		resolvers.forEach(resolver ->
 				Assert.isInstanceOf(SyncHandlerMethodArgumentResolver.class, resolver,
-						"Expected sync argument resolver: " + resolver.getClass().getName()));
+						"SyncHandlerMethodArgumentResolver requires SyncHandlerMethodArgumentResolver"));
 		super.setArgumentResolvers(resolvers);
 	}
 
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandler.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandler.java
index 64d97e95812..ed8b4818b26 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandler.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandler.java
@@ -106,7 +106,6 @@ public class ResponseEntityResultHandler extends AbstractMessageWriterResultHand
 
 	@Override
 	public Mono handleResult(ServerWebExchange exchange, HandlerResult result) {
-
 		ResolvableType returnType = result.getReturnType();
 		MethodParameter bodyType;
 
@@ -117,7 +116,7 @@ public class ResponseEntityResultHandler extends AbstractMessageWriterResultHand
 		ReactiveAdapter adapter = getAdapterRegistry().getAdapter(rawClass, optionalValue);
 
 		if (adapter != null) {
-			Assert.isTrue(!adapter.isMultiValue(), "Only a single ResponseEntity supported.");
+			Assert.isTrue(!adapter.isMultiValue(), "Only a single ResponseEntity supported");
 			returnValueMono = Mono.from(adapter.toPublisher(optionalValue));
 			bodyType = new MethodParameter(result.getReturnTypeSource());
 			bodyType.increaseNestingLevel();
@@ -130,8 +129,7 @@ public class ResponseEntityResultHandler extends AbstractMessageWriterResultHand
 		}
 
 		return returnValueMono.then(returnValue -> {
-
-			Assert.isInstanceOf(HttpEntity.class, returnValue);
+			Assert.isInstanceOf(HttpEntity.class, returnValue, "HttpEntity expected");
 			HttpEntity httpEntity = (HttpEntity) returnValue;
 
 			if (httpEntity instanceof ResponseEntity) {
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/view/script/ScriptTemplateView.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/view/script/ScriptTemplateView.java
index b50c708288b..0046be875a6 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/view/script/ScriptTemplateView.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/result/view/script/ScriptTemplateView.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -111,7 +111,7 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 	 * See {@link ScriptTemplateConfigurer#setEngine(ScriptEngine)} documentation.
 	 */
 	public void setEngine(ScriptEngine engine) {
-		Assert.isInstanceOf(Invocable.class, engine);
+		Assert.isInstanceOf(Invocable.class, engine, "ScriptEngine must implement Invocable");
 		this.engine = engine;
 	}
 
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/adapter/JettyWebSocketSession.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/adapter/JettyWebSocketSession.java
index 8beb4cd290c..ae95e9fc0e1 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/adapter/JettyWebSocketSession.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/adapter/JettyWebSocketSession.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,7 +44,7 @@ import org.springframework.web.reactive.socket.WebSocketSession;
  */
 public class JettyWebSocketSession extends AbstractListenerWebSocketSession {
 
-	private SuspendToken suspendToken;
+	private volatile SuspendToken suspendToken;
 
 
 	public JettyWebSocketSession(Session session, HandshakeInfo info, DataBufferFactory factory) {
@@ -65,14 +65,15 @@ public class JettyWebSocketSession extends AbstractListenerWebSocketSession protocol;
 
-
 		public WebSocketHandlerContainer(JettyWebSocketHandlerAdapter adapter, Optional protocol) {
 			this.adapter = adapter;
 			this.protocol = protocol;
@@ -194,4 +193,5 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Life
 			return this.protocol;
 		}
 	}
+
 }
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/TomcatRequestUpgradeStrategy.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/TomcatRequestUpgradeStrategy.java
index 7bfcce57b09..266982db8af 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/TomcatRequestUpgradeStrategy.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/TomcatRequestUpgradeStrategy.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,7 +20,6 @@ import java.io.IOException;
 import java.security.Principal;
 import java.util.Collections;
 import java.util.Optional;
-import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
@@ -35,8 +34,8 @@ import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.http.server.reactive.ServletServerHttpRequest;
 import org.springframework.http.server.reactive.ServletServerHttpResponse;
 import org.springframework.util.Assert;
-import org.springframework.web.reactive.socket.WebSocketHandler;
 import org.springframework.web.reactive.socket.HandshakeInfo;
+import org.springframework.web.reactive.socket.WebSocketHandler;
 import org.springframework.web.reactive.socket.adapter.StandardWebSocketHandlerAdapter;
 import org.springframework.web.reactive.socket.adapter.StandardWebSocketSession;
 import org.springframework.web.reactive.socket.server.RequestUpgradeStrategy;
@@ -55,9 +54,7 @@ public class TomcatRequestUpgradeStrategy implements RequestUpgradeStrategy {
 
 
 	@Override
-	public Mono upgrade(ServerWebExchange exchange, WebSocketHandler handler,
-			Optional subProtocol){
-
+	public Mono upgrade(ServerWebExchange exchange, WebSocketHandler handler, Optional subProtocol){
 		ServerHttpRequest request = exchange.getRequest();
 		ServerHttpResponse response = exchange.getResponse();
 
@@ -87,12 +84,12 @@ public class TomcatRequestUpgradeStrategy implements RequestUpgradeStrategy {
 	}
 
 	private HttpServletRequest getHttpServletRequest(ServerHttpRequest request) {
-		Assert.isTrue(request instanceof ServletServerHttpRequest);
+		Assert.isInstanceOf(ServletServerHttpRequest.class, request, "ServletServerHttpRequest required");
 		return ((ServletServerHttpRequest) request).getServletRequest();
 	}
 
 	private HttpServletResponse getHttpServletResponse(ServerHttpResponse response) {
-		Assert.isTrue(response instanceof ServletServerHttpResponse);
+		Assert.isInstanceOf(ServletServerHttpResponse.class, response, "ServletServerHttpResponse required");
 		return ((ServletServerHttpResponse) response).getServletResponse();
 	}
 
@@ -103,12 +100,9 @@ public class TomcatRequestUpgradeStrategy implements RequestUpgradeStrategy {
 	}
 
 	private WsServerContainer getContainer(HttpServletRequest request) {
-		ServletContext servletContext = request.getServletContext();
-		Object container = servletContext.getAttribute(SERVER_CONTAINER_ATTR);
-		Assert.notNull(container,
-				"No 'javax.websocket.server.ServerContainer' ServletContext attribute. " +
-						"Are you running in a Servlet container that supports JSR-356?");
-		Assert.isTrue(container instanceof WsServerContainer);
+		Object container = request.getServletContext().getAttribute(SERVER_CONTAINER_ATTR);
+		Assert.state(container instanceof WsServerContainer,
+				"No 'javax.websocket.server.ServerContainer' ServletContext attribute in a Tomcat container");
 		return (WsServerContainer) container;
 	}
 
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/UndertowRequestUpgradeStrategy.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/UndertowRequestUpgradeStrategy.java
index a0d5e77bb29..52d228753a5 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/UndertowRequestUpgradeStrategy.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/UndertowRequestUpgradeStrategy.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -53,13 +53,10 @@ import org.springframework.web.server.ServerWebExchange;
 @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
 public class UndertowRequestUpgradeStrategy implements RequestUpgradeStrategy {
 
-
 	@Override
-	public Mono upgrade(ServerWebExchange exchange, WebSocketHandler handler,
-			Optional subProtocol) {
-
+	public Mono upgrade(ServerWebExchange exchange, WebSocketHandler handler, Optional subProtocol) {
 		ServerHttpRequest request = exchange.getRequest();
-		Assert.isTrue(request instanceof UndertowServerHttpRequest);
+		Assert.isInstanceOf(UndertowServerHttpRequest.class, request, "UndertowServerHttpRequest required");
 		HttpServerExchange httpExchange = ((UndertowServerHttpRequest) request).getUndertowExchange();
 
 		Set protocols = subProtocol.map(Collections::singleton).orElse(Collections.emptySet());
@@ -92,10 +89,7 @@ public class UndertowRequestUpgradeStrategy implements RequestUpgradeStrategy {
 
 		private final DataBufferFactory bufferFactory;
 
-
-		public DefaultCallback(HandshakeInfo handshakeInfo, WebSocketHandler handler,
-				DataBufferFactory bufferFactory) {
-
+		public DefaultCallback(HandshakeInfo handshakeInfo, WebSocketHandler handler, DataBufferFactory bufferFactory) {
 			this.handshakeInfo = handshakeInfo;
 			this.handler = handler;
 			this.bufferFactory = bufferFactory;
@@ -103,7 +97,6 @@ public class UndertowRequestUpgradeStrategy implements RequestUpgradeStrategy {
 
 		@Override
 		public void onConnect(WebSocketHttpExchange httpExchange, WebSocketChannel channel) {
-
 			UndertowWebSocketSession session = createSession(channel);
 			UndertowWebSocketHandlerAdapter adapter = new UndertowWebSocketHandlerAdapter(session);
 
diff --git a/spring-web-reactive/src/test/java/org/springframework/web/reactive/FlushingIntegrationTests.java b/spring-web-reactive/src/test/java/org/springframework/web/reactive/FlushingIntegrationTests.java
index 5e72bcea6d1..18810cfd575 100644
--- a/spring-web-reactive/src/test/java/org/springframework/web/reactive/FlushingIntegrationTests.java
+++ b/spring-web-reactive/src/test/java/org/springframework/web/reactive/FlushingIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,13 +35,14 @@ import org.springframework.http.server.reactive.HttpHandler;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.http.server.reactive.bootstrap.RxNettyHttpServer;
-import org.springframework.util.Assert;
 import org.springframework.web.reactive.function.BodyExtractors;
 import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.reactive.function.client.WebClientOperations;
 import org.springframework.web.util.DefaultUriBuilderFactory;
 import org.springframework.web.util.UriBuilderFactory;
 
+import static org.junit.Assert.*;
+
 /**
  * @author Sebastien Deleuze
  */
@@ -52,8 +53,7 @@ public class FlushingIntegrationTests extends AbstractHttpHandlerIntegrationTest
 
 	@Before
 	public void setup() throws Exception {
-
-		// TODO: fix failing tests
+		// TODO: fix failing RxNetty tests
 		Assume.assumeFalse(this.server instanceof RxNettyHttpServer);
 
 		super.setup();
@@ -88,7 +88,7 @@ public class FlushingIntegrationTests extends AbstractHttpHandlerIntegrationTest
 				.reduce((s1, s2) -> s1 + s2);
 
 		StepVerifier.create(result)
-				.consumeNextWith(value -> Assert.isTrue(value.length() == 200000))
+				.consumeNextWith(value -> assertTrue(value.length() == 200000))
 				.expectComplete()
 				.verify(Duration.ofSeconds(10L));
 	}
diff --git a/spring-web-reactive/src/test/java/org/springframework/web/reactive/result/ResolvableMethod.java b/spring-web-reactive/src/test/java/org/springframework/web/reactive/result/ResolvableMethod.java
index 0b572755bc9..ca5105f24ab 100644
--- a/spring-web-reactive/src/test/java/org/springframework/web/reactive/result/ResolvableMethod.java
+++ b/spring-web-reactive/src/test/java/org/springframework/web/reactive/result/ResolvableMethod.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.web.reactive.result;
 
 import java.lang.annotation.Annotation;
@@ -70,7 +71,6 @@ public class ResolvableMethod {
 
 	private final Object object;
 
-
 	private String methodName;
 
 	private Class[] argumentTypes;
@@ -84,13 +84,13 @@ public class ResolvableMethod {
 
 
 	private ResolvableMethod(Class objectClass) {
-		Assert.notNull(objectClass);
+		Assert.notNull(objectClass, "Class must not be null");
 		this.objectClass = objectClass;
 		this.object = null;
 	}
 
 	private ResolvableMethod(Object object) {
-		Assert.notNull(object);
+		Assert.notNull(object, "Object must not be null");
 		this.object = object;
 		this.objectClass = object.getClass();
 	}
@@ -136,6 +136,7 @@ public class ResolvableMethod {
 		return this;
 	}
 
+
 	// Resolve methods
 
 	public Method resolve() {
@@ -168,18 +169,17 @@ public class ResolvableMethod {
 					return true;
 				});
 
-		Assert.isTrue(!methods.isEmpty(), "No matching method: " + this);
-		Assert.isTrue(methods.size() == 1, "Multiple matching methods: " + this);
-
+		Assert.state(!methods.isEmpty(), () -> "No matching method: " + this);
+		Assert.state(methods.size() == 1, () -> "Multiple matching methods: " + this);
 		return methods.iterator().next();
 	}
 
 	private String getReturnType() {
-		return this.returnType != null ? this.returnType.toString() : null;
+		return (this.returnType != null ? this.returnType.toString() : null);
 	}
 
 	public InvocableHandlerMethod resolveHandlerMethod() {
-		Assert.notNull(this.object);
+		Assert.state(this.object != null, "Object must not be null");
 		return new InvocableHandlerMethod(this.object, resolve());
 	}
 
@@ -194,9 +194,7 @@ public class ResolvableMethod {
 	}
 
 	@SafeVarargs
-	public final MethodParameter resolveParam(ResolvableType type,
-			Predicate... predicates) {
-
+	public final MethodParameter resolveParam(ResolvableType type, Predicate... predicates) {
 		List matches = new ArrayList<>();
 
 		Method method = resolve();
@@ -215,9 +213,8 @@ public class ResolvableMethod {
 			matches.add(param);
 		}
 
-		Assert.isTrue(!matches.isEmpty(), "No matching arg on " + method.toString());
-		Assert.isTrue(matches.size() == 1, "Multiple matching args: " + matches + " on " + method.toString());
-
+		Assert.state(!matches.isEmpty(), () -> "No matching arg on " + method.toString());
+		Assert.state(matches.size() == 1, () -> "Multiple matching args: " + matches + " on " + method.toString());
 		return matches.get(0);
 	}
 
@@ -238,4 +235,4 @@ public class ResolvableMethod {
 		return new ResolvableMethod(object);
 	}
 
-}
\ No newline at end of file
+}
diff --git a/spring-web-reactive/src/test/java/org/springframework/web/reactive/result/method/annotation/ModelAttributeMethodArgumentResolverTests.java b/spring-web-reactive/src/test/java/org/springframework/web/reactive/result/method/annotation/ModelAttributeMethodArgumentResolverTests.java
index 50989f74f1e..8387cc975dd 100644
--- a/spring-web-reactive/src/test/java/org/springframework/web/reactive/result/method/annotation/ModelAttributeMethodArgumentResolverTests.java
+++ b/spring-web-reactive/src/test/java/org/springframework/web/reactive/result/method/annotation/ModelAttributeMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.web.reactive.result.method.annotation;
 
 import java.net.URISyntaxException;
@@ -43,18 +44,12 @@ import org.springframework.web.reactive.result.ResolvableMethod;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.adapter.DefaultServerWebExchange;
 
-import static junit.framework.TestCase.assertNotNull;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
-import static org.springframework.core.ResolvableType.forClass;
-import static org.springframework.core.ResolvableType.forClassWithGenerics;
-import static org.springframework.util.Assert.isTrue;
-
+import static org.junit.Assert.*;
+import static org.springframework.core.ResolvableType.*;
 
 /**
  * Unit tests for {@link ModelAttributeMethodArgumentResolver}.
+ *
  * @author Rossen Stoyanchev
  */
 public class ModelAttributeMethodArgumentResolverTests {
@@ -208,7 +203,7 @@ public class ModelAttributeMethodArgumentResolverTests {
 				resolvedArgumentMono -> {
 					Object value = resolvedArgumentMono.blockMillis(5000);
 					assertNotNull(value);
-					isTrue(value instanceof Mono);
+					assertTrue(value instanceof Mono);
 					return (Mono) value;
 				});
 	}
@@ -220,14 +215,13 @@ public class ModelAttributeMethodArgumentResolverTests {
 				resolvedArgumentMono -> {
 					Object value = resolvedArgumentMono.blockMillis(5000);
 					assertNotNull(value);
-					isTrue(value instanceof Single);
+					assertTrue(value instanceof Single);
 					return Mono.from(RxReactiveStreams.toPublisher((Single) value));
 				});
 	}
 
 
 	private void testBindFoo(ResolvableType type, Function valueExtractor) throws Exception {
-
 		Object value = createResolver()
 				.resolveArgument(parameter(type), this.bindContext, exchange("name=Robert&age=25"))
 				.blockMillis(0);
diff --git a/spring-web/src/main/java/org/springframework/http/ContentDisposition.java b/spring-web/src/main/java/org/springframework/http/ContentDisposition.java
index a7ab9da5639..a2dd5baece3 100644
--- a/spring-web/src/main/java/org/springframework/http/ContentDisposition.java
+++ b/spring-web/src/main/java/org/springframework/http/ContentDisposition.java
@@ -23,8 +23,7 @@ import java.nio.charset.StandardCharsets;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
-import static java.nio.charset.StandardCharsets.ISO_8859_1;
-import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.nio.charset.StandardCharsets.*;
 
 /**
  * Represent the content disposition type and parameters as defined in RFC 2183.
@@ -121,7 +120,7 @@ public class ContentDisposition {
 	 */
 	public static ContentDisposition parse(String contentDisposition) {
 		String[] parts = StringUtils.tokenizeToStringArray(contentDisposition, ";");
-		Assert.isTrue(parts.length >= 1);
+		Assert.isTrue(parts.length >= 1, "Content-Disposition header must not be empty");
 		String type = parts[0];
 		String name = null;
 		String filename = null;
diff --git a/spring-web/src/main/java/org/springframework/http/ResponseCookie.java b/spring-web/src/main/java/org/springframework/http/ResponseCookie.java
index 524a82a42ac..decc77a0cff 100644
--- a/spring-web/src/main/java/org/springframework/http/ResponseCookie.java
+++ b/spring-web/src/main/java/org/springframework/http/ResponseCookie.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.http;
 
 import java.time.Duration;
@@ -50,7 +51,7 @@ public final class ResponseCookie extends HttpCookie {
 			String path, boolean secure, boolean httpOnly) {
 
 		super(name, value);
-		Assert.notNull(maxAge);
+		Assert.notNull(maxAge, "Max age must not be null");
 		this.maxAge = maxAge;
 		this.domain = Optional.ofNullable(domain);
 		this.path = Optional.ofNullable(path);
@@ -61,7 +62,6 @@ public final class ResponseCookie extends HttpCookie {
 
 	/**
 	 * Return the cookie "Max-Age" attribute in seconds.
-	 *
 	 * 
A positive value indicates when the cookie expires relative to the
 	 * current time. A value of 0 means the cookie should expire immediately.
 	 * A negative value means no "Max-Age" attribute in which case the cookie
@@ -100,13 +100,6 @@ public final class ResponseCookie extends HttpCookie {
 		return this.httpOnly;
 	}
 
-	@Override
-	public int hashCode() {
-		int result = super.hashCode();
-		result = 31 * result + ObjectUtils.nullSafeHashCode(this.domain);
-		result = 31 * result + ObjectUtils.nullSafeHashCode(this.path);
-		return result;
-	}
 
 	@Override
 	public boolean equals(Object other) {
@@ -122,6 +115,14 @@ public final class ResponseCookie extends HttpCookie {
 				ObjectUtils.nullSafeEquals(this.domain, otherCookie.getDomain()));
 	}
 
+	@Override
+	public int hashCode() {
+		int result = super.hashCode();
+		result = 31 * result + ObjectUtils.nullSafeHashCode(this.domain);
+		result = 31 * result + ObjectUtils.nullSafeHashCode(this.path);
+		return result;
+	}
+
 
 	/**
 	 * Factory method to obtain a builder for a server-defined cookie that starts
@@ -144,7 +145,6 @@ public final class ResponseCookie extends HttpCookie {
 
 			private boolean httpOnly;
 
-
 			@Override
 			public ResponseCookieBuilder maxAge(Duration maxAge) {
 				this.maxAge = maxAge;
@@ -189,6 +189,7 @@ public final class ResponseCookie extends HttpCookie {
 		};
 	}
 
+
 	/**
 	 * A builder for a server-defined HttpCookie with attributes.
 	 */
diff --git a/spring-web/src/main/java/org/springframework/http/client/SimpleClientHttpRequestFactory.java b/spring-web/src/main/java/org/springframework/http/client/SimpleClientHttpRequestFactory.java
index bf982d6e240..3aff0c92213 100644
--- a/spring-web/src/main/java/org/springframework/http/client/SimpleClientHttpRequestFactory.java
+++ b/spring-web/src/main/java/org/springframework/http/client/SimpleClientHttpRequestFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -177,7 +177,9 @@ public class SimpleClientHttpRequestFactory implements ClientHttpRequestFactory,
 	 */
 	protected HttpURLConnection openConnection(URL url, Proxy proxy) throws IOException {
 		URLConnection urlConnection = (proxy != null ? url.openConnection(proxy) : url.openConnection());
-		Assert.isInstanceOf(HttpURLConnection.class, urlConnection);
+		if (!HttpURLConnection.class.isInstance(urlConnection)) {
+			throw new IllegalStateException("HttpURLConnection required for [" + url + "] but got: " + urlConnection);
+		}
 		return (HttpURLConnection) urlConnection;
 	}
 
diff --git a/spring-web/src/main/java/org/springframework/http/client/reactive/AbstractClientHttpRequest.java b/spring-web/src/main/java/org/springframework/http/client/reactive/AbstractClientHttpRequest.java
index 3c0d5c4813b..c76d0bc786e 100644
--- a/spring-web/src/main/java/org/springframework/http/client/reactive/AbstractClientHttpRequest.java
+++ b/spring-web/src/main/java/org/springframework/http/client/reactive/AbstractClientHttpRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,6 +49,7 @@ public abstract class AbstractClientHttpRequest implements ClientHttpRequest {
 	 */
 	private enum State {NEW, COMMITTING, COMMITTED}
 
+
 	private final HttpHeaders headers;
 
 	private final MultiValueMap cookies;
@@ -63,7 +64,7 @@ public abstract class AbstractClientHttpRequest implements ClientHttpRequest {
 	}
 
 	public AbstractClientHttpRequest(HttpHeaders headers) {
-		Assert.notNull(headers);
+		Assert.notNull(headers, "HttpHeaders must not be null");
 		this.headers = headers;
 		this.cookies = new LinkedMultiValueMap<>();
 	}
@@ -124,7 +125,7 @@ public abstract class AbstractClientHttpRequest implements ClientHttpRequest {
 
 	@Override
 	public void beforeCommit(Supplier> action) {
-		Assert.notNull(action);
+		Assert.notNull(action, "Action must not be null");
 		this.commitActions.add(action);
 	}
 
@@ -140,5 +141,4 @@ public abstract class AbstractClientHttpRequest implements ClientHttpRequest {
 	 */
 	protected abstract void applyCookies();
 
-
-}
\ No newline at end of file
+}
diff --git a/spring-web/src/main/java/org/springframework/http/converter/cbor/MappingJackson2CborHttpMessageConverter.java b/spring-web/src/main/java/org/springframework/http/converter/cbor/MappingJackson2CborHttpMessageConverter.java
index 4a3dcb5e284..b08f59dd464 100644
--- a/spring-web/src/main/java/org/springframework/http/converter/cbor/MappingJackson2CborHttpMessageConverter.java
+++ b/spring-web/src/main/java/org/springframework/http/converter/cbor/MappingJackson2CborHttpMessageConverter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,16 +58,17 @@ public class MappingJackson2CborHttpMessageConverter extends AbstractJackson2Htt
 	 */
 	public MappingJackson2CborHttpMessageConverter(ObjectMapper objectMapper) {
 		super(objectMapper, new MediaType("application", "cbor"));
-		Assert.isAssignable(CBORFactory.class, objectMapper.getFactory().getClass());
+		Assert.isInstanceOf(CBORFactory.class, objectMapper.getFactory(), "CBORFactory required");
 	}
 
+
 	/**
 	 * {@inheritDoc}
-	 * The {@code objectMapper} parameter must be configured with a {@code CBORFactory} instance.
+	 * The {@code ObjectMapper} must be configured with a {@code CBORFactory} instance.
 	 */
 	@Override
 	public void setObjectMapper(ObjectMapper objectMapper) {
-		Assert.isAssignable(CBORFactory.class, objectMapper.getFactory().getClass());
+		Assert.isInstanceOf(CBORFactory.class, objectMapper.getFactory(), "CBORFactory required");
 		super.setObjectMapper(objectMapper);
 	}
 
diff --git a/spring-web/src/main/java/org/springframework/http/converter/smile/MappingJackson2SmileHttpMessageConverter.java b/spring-web/src/main/java/org/springframework/http/converter/smile/MappingJackson2SmileHttpMessageConverter.java
index 5d5040b85e7..e70694d4061 100644
--- a/spring-web/src/main/java/org/springframework/http/converter/smile/MappingJackson2SmileHttpMessageConverter.java
+++ b/spring-web/src/main/java/org/springframework/http/converter/smile/MappingJackson2SmileHttpMessageConverter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,16 +58,17 @@ public class MappingJackson2SmileHttpMessageConverter extends AbstractJackson2Ht
 	 */
 	public MappingJackson2SmileHttpMessageConverter(ObjectMapper objectMapper) {
 		super(objectMapper, new MediaType("application", "x-jackson-smile"));
-		Assert.isAssignable(SmileFactory.class, objectMapper.getFactory().getClass());
+		Assert.isInstanceOf(SmileFactory.class, objectMapper.getFactory(), "SmileFactory required");
 	}
 
+
 	/**
 	 * {@inheritDoc}
-	 * The {@code objectMapper} parameter must be configured with a {@code SmileFactory} instance.
+	 * The {@code ObjectMapper} must be configured with a {@code SmileFactory} instance.
 	 */
 	@Override
 	public void setObjectMapper(ObjectMapper objectMapper) {
-		Assert.isAssignable(SmileFactory.class, objectMapper.getFactory().getClass());
+		Assert.isInstanceOf(SmileFactory.class, objectMapper.getFactory(), "SmileFactory required");
 		super.setObjectMapper(objectMapper);
 	}
 
diff --git a/spring-web/src/main/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverter.java b/spring-web/src/main/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverter.java
index 39eb13ef676..a829385634f 100644
--- a/spring-web/src/main/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverter.java
+++ b/spring-web/src/main/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -60,16 +60,17 @@ public class MappingJackson2XmlHttpMessageConverter extends AbstractJackson2Http
 		super(objectMapper, new MediaType("application", "xml"),
 				new MediaType("text", "xml"),
 				new MediaType("application", "*+xml"));
-		Assert.isAssignable(XmlMapper.class, objectMapper.getClass());
+		Assert.isInstanceOf(XmlMapper.class, objectMapper, "XmlMapper required");
 	}
 
+
 	/**
 	 * {@inheritDoc}
-	 * The {@code objectMapper} parameter must be a {@link XmlMapper} instance.
+	 * The {@code ObjectMapper} parameter must be a {@link XmlMapper} instance.
 	 */
 	@Override
 	public void setObjectMapper(ObjectMapper objectMapper) {
-		Assert.isAssignable(XmlMapper.class, objectMapper.getClass());
+		Assert.isInstanceOf(XmlMapper.class, objectMapper, "XmlMapper required");
 		super.setObjectMapper(objectMapper);
 	}
 
diff --git a/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java b/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java
index c8e1ecb86b0..26cdc9f37e4 100644
--- a/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java
+++ b/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -181,7 +181,9 @@ public class ServletServerHttpRequest implements ServerHttpRequest {
 	@Override
 	public ServerHttpAsyncRequestControl getAsyncRequestControl(ServerHttpResponse response) {
 		if (this.asyncRequestControl == null) {
-			Assert.isInstanceOf(ServletServerHttpResponse.class, response);
+			if (!ServletServerHttpResponse.class.isInstance(response)) {
+				throw new IllegalArgumentException("Response must be a ServletServerHttpResponse: " + response.getClass());
+			}
 			ServletServerHttpResponse servletServerResponse = (ServletServerHttpResponse) response;
 			this.asyncRequestControl = new ServletServerHttpAsyncRequestControl(this, servletServerResponse);
 		}
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerReadPublisher.java b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerReadPublisher.java
index 2b9c682cee2..fe4f0a6f564 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerReadPublisher.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerReadPublisher.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +17,6 @@
 package org.springframework.http.server.reactive;
 
 import java.io.IOException;
-import java.util.Objects;
 import java.util.concurrent.atomic.AtomicLongFieldUpdater;
 import java.util.concurrent.atomic.AtomicReference;
 
@@ -28,6 +27,8 @@ import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 import reactor.core.publisher.Operators;
 
+import org.springframework.util.Assert;
+
 /**
  * Abstract base class for {@code Publisher} implementations that bridge between
  * event-listener read APIs and Reactive Streams.
@@ -48,6 +49,7 @@ public abstract class AbstractListenerReadPublisher implements Publisher {
 
 	private final AtomicReference state = new AtomicReference<>(State.UNSUBSCRIBED);
 
+	@SuppressWarnings("unused")
 	private volatile long demand;
 
 	@SuppressWarnings("rawtypes")
@@ -196,7 +198,8 @@ public abstract class AbstractListenerReadPublisher implements Publisher {
 		UNSUBSCRIBED {
 			@Override
 			 void subscribe(AbstractListenerReadPublisher publisher, Subscriber subscriber) {
-				Objects.requireNonNull(subscriber);
+				Assert.notNull(publisher, "Publisher must not be null");
+				Assert.notNull(subscriber, "Subscriber must not be null");
 				if (publisher.changeState(this, NO_DEMAND)) {
 					Subscription subscription = new ReadSubscription(publisher);
 					publisher.subscriber = subscriber;
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteFlushProcessor.java b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteFlushProcessor.java
index 4053fd30100..42797152a6e 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteFlushProcessor.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteFlushProcessor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +17,6 @@
 package org.springframework.http.server.reactive;
 
 import java.io.IOException;
-import java.util.Objects;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.apache.commons.logging.Log;
@@ -27,6 +26,8 @@ import org.reactivestreams.Publisher;
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 
+import org.springframework.util.Assert;
+
 /**
  * An alternative to {@link AbstractListenerWriteProcessor} but instead writing
  * a {@code Publisher>} with flush boundaries enforces after
@@ -127,10 +128,9 @@ public abstract class AbstractListenerWriteFlushProcessor implements Processo
 	private enum State {
 
 		UNSUBSCRIBED {
-
 			@Override
 			public  void onSubscribe(AbstractListenerWriteFlushProcessor processor, Subscription subscription) {
-				Objects.requireNonNull(subscription, "Subscription cannot be null");
+				Assert.notNull(subscription, "Subscription must not be null");
 				if (processor.changeState(this, REQUESTED)) {
 					processor.subscription = subscription;
 					subscription.request(1);
@@ -140,8 +140,8 @@ public abstract class AbstractListenerWriteFlushProcessor implements Processo
 				}
 			}
 		},
-		REQUESTED {
 
+		REQUESTED {
 			@Override
 			public  void onNext(AbstractListenerWriteFlushProcessor processor, Publisher chunk) {
 				if (processor.changeState(this, RECEIVED)) {
@@ -150,7 +150,6 @@ public abstract class AbstractListenerWriteFlushProcessor implements Processo
 					chunkProcessor.subscribe(new WriteSubscriber(processor));
 				}
 			}
-
 			@Override
 			public  void onComplete(AbstractListenerWriteFlushProcessor processor) {
 				if (processor.changeState(this, COMPLETED)) {
@@ -158,8 +157,8 @@ public abstract class AbstractListenerWriteFlushProcessor implements Processo
 				}
 			}
 		},
-		RECEIVED {
 
+		RECEIVED {
 			@Override
 			public  void writeComplete(AbstractListenerWriteFlushProcessor processor) {
 				try {
@@ -169,7 +168,6 @@ public abstract class AbstractListenerWriteFlushProcessor implements Processo
 					processor.cancel();
 					processor.onError(ex);
 				}
-
 				if (processor.subscriberCompleted) {
 					if (processor.changeState(this, COMPLETED)) {
 						processor.resultPublisher.publishComplete();
@@ -181,26 +179,21 @@ public abstract class AbstractListenerWriteFlushProcessor implements Processo
 					}
 				}
 			}
-
 			@Override
 			public  void onComplete(AbstractListenerWriteFlushProcessor processor) {
 				processor.subscriberCompleted = true;
 			}
 		},
-		COMPLETED {
 
+		COMPLETED {
 			@Override
-			public  void onNext(AbstractListenerWriteFlushProcessor processor,
-					Publisher publisher) {
+			public  void onNext(AbstractListenerWriteFlushProcessor processor, Publisher publisher) {
 				// ignore
-
 			}
-
 			@Override
 			public  void onError(AbstractListenerWriteFlushProcessor processor, Throwable t) {
 				// ignore
 			}
-
 			@Override
 			public  void onComplete(AbstractListenerWriteFlushProcessor processor) {
 				// ignore
@@ -234,7 +227,6 @@ public abstract class AbstractListenerWriteFlushProcessor implements Processo
 
 			private final AbstractListenerWriteFlushProcessor processor;
 
-
 			public WriteSubscriber(AbstractListenerWriteFlushProcessor processor) {
 				this.processor = processor;
 			}
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteProcessor.java b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteProcessor.java
index 55ea82967a4..eb1bbccd8bf 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteProcessor.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteProcessor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +17,6 @@
 package org.springframework.http.server.reactive;
 
 import java.io.IOException;
-import java.util.Objects;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.apache.commons.logging.Log;
@@ -120,7 +119,9 @@ public abstract class AbstractListenerWriteProcessor implements Processor implements Processor void onSubscribe(AbstractListenerWriteProcessor processor, Subscription subscription) {
-				Objects.requireNonNull(subscription, "Subscription cannot be null");
+				Assert.notNull(subscription, "Subscription must not be null");
 				if (processor.changeState(this, REQUESTED)) {
 					processor.subscription = subscription;
 					subscription.request(1);
@@ -198,6 +198,7 @@ public abstract class AbstractListenerWriteProcessor implements Processor implements Processor void onNext(AbstractListenerWriteProcessor processor, T data) {
 				if (processor.isDataEmpty(data)) {
@@ -218,7 +218,6 @@ public abstract class AbstractListenerWriteProcessor implements Processor void onComplete(AbstractListenerWriteProcessor processor) {
 				if (processor.changeState(this, COMPLETED)) {
@@ -226,6 +225,7 @@ public abstract class AbstractListenerWriteProcessor implements Processor implements Processor void onWritePossible(AbstractListenerWriteProcessor processor) {
 				if (processor.changeState(this, WRITING)) {
@@ -265,38 +264,35 @@ public abstract class AbstractListenerWriteProcessor implements Processor void onComplete(AbstractListenerWriteProcessor processor) {
 				processor.subscriberCompleted = true;
 			}
 		},
+
 		/**
 		 * State that gets entered after a writing of the current data has been
 		 * {@code onWritePossible started}.
 		 */
 		WRITING {
-
 			@Override
 			public  void onComplete(AbstractListenerWriteProcessor processor) {
 				processor.subscriberCompleted = true;
 			}
 		},
+
 		/**
 		 * The terminal completed state. Does not respond to any events.
 		 */
 		COMPLETED {
-
 			@Override
 			public  void onNext(AbstractListenerWriteProcessor processor, T data) {
 				// ignore
 			}
-
 			@Override
 			public  void onError(AbstractListenerWriteProcessor processor, Throwable ex) {
 				// ignore
 			}
-
 			@Override
 			public  void onComplete(AbstractListenerWriteProcessor processor) {
 				// ignore
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractServerHttpResponse.java b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractServerHttpResponse.java
index ac871739204..91e6d7dd79c 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractServerHttpResponse.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractServerHttpResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -89,7 +89,7 @@ public abstract class AbstractServerHttpResponse implements ServerHttpResponse {
 
 	@Override
 	public boolean setStatusCode(HttpStatus statusCode) {
-		Assert.notNull(statusCode);
+		Assert.notNull(statusCode, "Status code must not be null");
 		if (this.state.get() == State.COMMITTED) {
 			if (logger.isDebugEnabled()) {
 				logger.debug("Can't set the status " + statusCode.toString() +
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/HttpHandlerAdapterSupport.java b/spring-web/src/main/java/org/springframework/http/server/reactive/HttpHandlerAdapterSupport.java
index 16c535cc187..bac06a1635d 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/HttpHandlerAdapterSupport.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/HttpHandlerAdapterSupport.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.http.server.reactive;
 
 import java.util.LinkedHashMap;
@@ -57,11 +58,9 @@ public abstract class HttpHandlerAdapterSupport {
 	/**
 	 * Constructor with {@code HttpHandler}s mapped to distinct context paths.
 	 * Context paths must start but not end with "/" and must be encoded.
-	 *
 	 * 
At request time context paths are compared against the "raw" path of
 	 * the request URI in the order in which they are provided. The first one
 	 * to match is chosen. If none match the response status is set to 404.
-	 *
 	 * @param handlerMap map with context paths and {@code HttpHandler}s.
 	 * @see ServerHttpRequest#getContextPath()
 	 */
@@ -85,9 +84,8 @@ public abstract class HttpHandlerAdapterSupport {
 
 		private final Map handlerMap;
 
-
 		public CompositeHttpHandler(Map handlerMap) {
-			Assert.notEmpty(handlerMap);
+			Assert.notEmpty(handlerMap, "Handler map must not be empty");
 			this.handlerMap = initHandlerMap(handlerMap);
 		}
 
@@ -97,10 +95,10 @@ public abstract class HttpHandlerAdapterSupport {
 		}
 
 		private static void validateContextPath(String contextPath) {
-			Assert.hasText(contextPath, "contextPath must not be empty");
+			Assert.hasText(contextPath, "Context path must not be empty");
 			if (!contextPath.equals("/")) {
-				Assert.isTrue(contextPath.startsWith("/"), "contextPath must begin with '/'");
-				Assert.isTrue(!contextPath.endsWith("/"), "contextPath must not end with '/'");
+				Assert.isTrue(contextPath.startsWith("/"), "Context path must begin with '/'");
+				Assert.isTrue(!contextPath.endsWith("/"), "Context path must not end with '/'");
 			}
 		}
 
@@ -124,7 +122,9 @@ public abstract class HttpHandlerAdapterSupport {
 					});
 		}
 
-		/** Strip the context path from native request if any */
+		/**
+		 * Strip the context path from the native request, if any.
+		 */
 		private String getPathToUse(ServerHttpRequest request) {
 			String path = request.getURI().getRawPath();
 			String contextPath = request.getContextPath();
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/ServletHttpHandlerAdapter.java b/spring-web/src/main/java/org/springframework/http/server/reactive/ServletHttpHandlerAdapter.java
index d46918aa726..ed5a4a4746d 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/ServletHttpHandlerAdapter.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/ServletHttpHandlerAdapter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,12 +50,12 @@ public class ServletHttpHandlerAdapter extends HttpHandlerAdapterSupport impleme
 	private static final int DEFAULT_BUFFER_SIZE = 8192;
 
 
+	private int bufferSize = DEFAULT_BUFFER_SIZE;
+
 	// Servlet is based on blocking I/O, hence the usage of non-direct, heap-based buffers
 	// (i.e. 'false' as constructor argument)
 	private DataBufferFactory dataBufferFactory = new DefaultDataBufferFactory(false);
 
-	private int bufferSize = DEFAULT_BUFFER_SIZE;
-
 
 	public ServletHttpHandlerAdapter(HttpHandler httpHandler) {
 		super(httpHandler);
@@ -66,21 +66,12 @@ public class ServletHttpHandlerAdapter extends HttpHandlerAdapterSupport impleme
 	}
 
 
-	public void setDataBufferFactory(DataBufferFactory dataBufferFactory) {
-		Assert.notNull(dataBufferFactory, "'dataBufferFactory' must not be null");
-		this.dataBufferFactory = dataBufferFactory;
-	}
-
-	public DataBufferFactory getDataBufferFactory() {
-		return this.dataBufferFactory;
-	}
-
 	/**
 	 * Set the size of the input buffer used for reading in bytes.
 	 * 
By default this is set to 8192.
 	 */
 	public void setBufferSize(int bufferSize) {
-		Assert.isTrue(bufferSize > 0);
+		Assert.isTrue(bufferSize > 0, "Buffer size must be larger than zero");
 		this.bufferSize = bufferSize;
 	}
 
@@ -91,10 +82,20 @@ public class ServletHttpHandlerAdapter extends HttpHandlerAdapterSupport impleme
 		return this.bufferSize;
 	}
 
+	public void setDataBufferFactory(DataBufferFactory dataBufferFactory) {
+		Assert.notNull(dataBufferFactory, "DataBufferFactory must not be null");
+		this.dataBufferFactory = dataBufferFactory;
+	}
+
+	public DataBufferFactory getDataBufferFactory() {
+		return this.dataBufferFactory;
+	}
+
+
+	// The Servlet.service method
 
 	@Override
 	public void service(ServletRequest request, ServletResponse response) throws IOException {
-
 		// Start async before Read/WriteListener registration
 		AsyncContext asyncContext = request.startAsync();
 
@@ -105,18 +106,15 @@ public class ServletHttpHandlerAdapter extends HttpHandlerAdapterSupport impleme
 		getHttpHandler().handle(httpRequest, httpResponse).subscribe(subscriber);
 	}
 
-	protected ServerHttpRequest createRequest(HttpServletRequest request, AsyncContext context)
-			throws IOException {
-
+	protected ServerHttpRequest createRequest(HttpServletRequest request, AsyncContext context) throws IOException {
 		return new ServletServerHttpRequest(request, context, getDataBufferFactory(), getBufferSize());
 	}
 
-	protected ServerHttpResponse createResponse(HttpServletResponse response, AsyncContext context)
-			throws IOException {
-
+	protected ServerHttpResponse createResponse(HttpServletResponse response, AsyncContext context) throws IOException {
 		return new ServletServerHttpResponse(response, context, getDataBufferFactory(), getBufferSize());
 	}
 
+
 	// Other Servlet methods...
 
 	@Override
@@ -142,7 +140,6 @@ public class ServletHttpHandlerAdapter extends HttpHandlerAdapterSupport impleme
 
 		private final AsyncContext asyncContext;
 
-
 		public HandlerResultSubscriber(AsyncContext asyncContext) {
 			this.asyncContext = asyncContext;
 		}
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/ServletServerHttpResponse.java b/spring-web/src/main/java/org/springframework/http/server/reactive/ServletServerHttpResponse.java
index c07c3840faf..63854ef3dc3 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/ServletServerHttpResponse.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/ServletServerHttpResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,6 +43,7 @@ import org.springframework.util.Assert;
 
 /**
  * Adapt {@link ServerHttpResponse} to the Servlet {@link HttpServletResponse}.
+ *
  * @author Rossen Stoyanchev
  * @since 5.0
  */
@@ -66,7 +67,7 @@ public class ServletServerHttpResponse extends AbstractListenerServerHttpRespons
 
 		Assert.notNull(response, "HttpServletResponse must not be null");
 		Assert.notNull(bufferFactory, "DataBufferFactory must not be null");
-		Assert.isTrue(bufferSize > 0, "'bufferSize' must be greater than 0");
+		Assert.isTrue(bufferSize > 0, "Buffer size must be greater than 0");
 
 		this.response = response;
 		this.bufferSize = bufferSize;
@@ -210,6 +211,7 @@ public class ServletServerHttpResponse extends AbstractListenerServerHttpRespons
 		}
 	}
 
+
 	private class ResponseBodyWriteListener implements WriteListener {
 
 		@Override
@@ -228,6 +230,7 @@ public class ServletServerHttpResponse extends AbstractListenerServerHttpRespons
 		}
 	}
 
+
 	private class ResponseBodyFlushProcessor extends AbstractListenerWriteFlushProcessor {
 
 		@Override
@@ -251,11 +254,11 @@ public class ServletServerHttpResponse extends AbstractListenerServerHttpRespons
 		}
 	}
 
+
 	private class ResponseBodyProcessor extends AbstractListenerWriteProcessor {
 
 		private final ServletOutputStream outputStream;
 
-
 		public ResponseBodyProcessor(ServletOutputStream outputStream) {
 			this.outputStream = outputStream;
 		}
@@ -268,7 +271,7 @@ public class ServletServerHttpResponse extends AbstractListenerServerHttpRespons
 		@Override
 		protected void releaseData() {
 			if (logger.isTraceEnabled()) {
-				logger.trace("releaseBuffer: " + this.currentData);
+				logger.trace("releaseData: " + this.currentData);
 			}
 			DataBufferUtils.release(this.currentData);
 			this.currentData = null;
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/UndertowServerHttpResponse.java b/spring-web/src/main/java/org/springframework/http/server/reactive/UndertowServerHttpResponse.java
index d43c4cb2665..bd16c86b810 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/UndertowServerHttpResponse.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/UndertowServerHttpResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,7 +30,6 @@ import io.undertow.server.handlers.CookieImpl;
 import io.undertow.util.HttpString;
 import org.reactivestreams.Processor;
 import org.reactivestreams.Publisher;
-import org.xnio.ChannelListener;
 import org.xnio.channels.StreamSinkChannel;
 import reactor.core.publisher.Mono;
 
@@ -60,7 +59,7 @@ public class UndertowServerHttpResponse extends AbstractListenerServerHttpRespon
 
 	public UndertowServerHttpResponse(HttpServerExchange exchange, DataBufferFactory bufferFactory) {
 		super(bufferFactory);
-		Assert.notNull(exchange, "'exchange' is required.");
+		Assert.notNull(exchange, "HttpServerExchange is required");
 		this.exchange = exchange;
 	}
 
@@ -69,6 +68,7 @@ public class UndertowServerHttpResponse extends AbstractListenerServerHttpRespon
 		return this.exchange;
 	}
 
+
 	@Override
 	protected void applyStatusCode() {
 		HttpStatus statusCode = this.getStatusCode();
@@ -145,15 +145,13 @@ public class UndertowServerHttpResponse extends AbstractListenerServerHttpRespon
 
 		private volatile ByteBuffer byteBuffer;
 
-
 		public ResponseBodyProcessor(StreamSinkChannel channel) {
 			Assert.notNull(channel, "StreamSinkChannel must not be null");
 			this.channel = channel;
 		}
 
-
 		public void registerListener() {
-			this.channel.getWriteSetter().set((ChannelListener) c -> onWritePossible());
+			this.channel.getWriteSetter().set(c -> onWritePossible());
 			this.channel.resumeWrites();
 		}
 
@@ -199,7 +197,7 @@ public class UndertowServerHttpResponse extends AbstractListenerServerHttpRespon
 		@Override
 		protected void releaseData() {
 			if (logger.isTraceEnabled()) {
-				logger.trace("releaseBuffer: " + this.currentData);
+				logger.trace("releaseData: " + this.currentData);
 			}
 			DataBufferUtils.release(this.currentData);
 			this.currentData = null;
@@ -209,10 +207,11 @@ public class UndertowServerHttpResponse extends AbstractListenerServerHttpRespon
 
 		@Override
 		protected boolean isDataEmpty(DataBuffer dataBuffer) {
-			return dataBuffer.readableByteCount() == 0;
+			return (dataBuffer.readableByteCount() == 0);
 		}
 	}
 
+
 	private class ResponseBodyFlushProcessor extends AbstractListenerWriteFlushProcessor {
 
 		@Override
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/WriteResultPublisher.java b/spring-web/src/main/java/org/springframework/http/server/reactive/WriteResultPublisher.java
index f239b9426b2..ed9e0a030bf 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/WriteResultPublisher.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/WriteResultPublisher.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,6 @@
 
 package org.springframework.http.server.reactive;
 
-import java.util.Objects;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.apache.commons.logging.Log;
@@ -26,6 +25,8 @@ import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 import reactor.core.publisher.Operators;
 
+import org.springframework.util.Assert;
+
 /**
  * Publisher returned from {@link ServerHttpResponse#writeWith(Publisher)}.
  *
@@ -113,12 +114,10 @@ class WriteResultPublisher implements Publisher {
 
 		UNSUBSCRIBED {
 			@Override
-			void subscribe(WriteResultPublisher publisher,
-					Subscriber subscriber) {
-				Objects.requireNonNull(subscriber);
+			void subscribe(WriteResultPublisher publisher, Subscriber subscriber) {
+				Assert.notNull(subscriber, "Subscriber must not be null");
 				if (publisher.changeState(this, SUBSCRIBED)) {
-					Subscription subscription =
-							new ResponseBodyWriteResultSubscription(publisher);
+					Subscription subscription = new ResponseBodyWriteResultSubscription(publisher);
 					publisher.subscriber = subscriber;
 					subscriber.onSubscribe(subscription);
 					if (publisher.publisherCompleted) {
diff --git a/spring-web/src/main/java/org/springframework/web/accept/PathExtensionContentNegotiationStrategy.java b/spring-web/src/main/java/org/springframework/web/accept/PathExtensionContentNegotiationStrategy.java
index 23bcc9c712d..438027a37de 100644
--- a/spring-web/src/main/java/org/springframework/web/accept/PathExtensionContentNegotiationStrategy.java
+++ b/spring-web/src/main/java/org/springframework/web/accept/PathExtensionContentNegotiationStrategy.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -136,15 +136,15 @@ public class PathExtensionContentNegotiationStrategy extends AbstractMappingCont
 
 	/**
 	 * A public method exposing the knowledge of the path extension strategy to
-	 * resolve file extensions to a MediaType in this case for a given
+	 * resolve file extensions to a {@link MediaType} in this case for a given
 	 * {@link Resource}. The method first looks up any explicitly registered
 	 * file extensions first and then falls back on JAF if available.
 	 * @param resource the resource to look up
-	 * @return the MediaType for the extension or {@code null}.
+	 * @return the MediaType for the extension, or {@code null} if none found
 	 * @since 4.3
 	 */
 	public MediaType getMediaTypeForResource(Resource resource) {
-		Assert.notNull(resource);
+		Assert.notNull(resource, "Resource must not be null");
 		MediaType mediaType = null;
 		String filename = resource.getFilename();
 		String extension = StringUtils.getFilenameExtension(filename);
diff --git a/spring-web/src/main/java/org/springframework/web/bind/UnsatisfiedServletRequestParameterException.java b/spring-web/src/main/java/org/springframework/web/bind/UnsatisfiedServletRequestParameterException.java
index cb274152e44..9b4c91add0c 100644
--- a/spring-web/src/main/java/org/springframework/web/bind/UnsatisfiedServletRequestParameterException.java
+++ b/spring-web/src/main/java/org/springframework/web/bind/UnsatisfiedServletRequestParameterException.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -64,7 +64,7 @@ public class UnsatisfiedServletRequestParameterException extends ServletRequestB
 			Map actualParams) {
 
 		super("");
-		Assert.isTrue(!CollectionUtils.isEmpty(paramConditions));
+		Assert.notEmpty(paramConditions, "Parameter conditions must not be empty");
 		this.paramConditions = paramConditions;
 		this.actualParams = actualParams;
 	}
diff --git a/spring-web/src/main/java/org/springframework/web/context/ContextLoader.java b/spring-web/src/main/java/org/springframework/web/context/ContextLoader.java
index 25cf45afdb8..85204e96b42 100644
--- a/spring-web/src/main/java/org/springframework/web/context/ContextLoader.java
+++ b/spring-web/src/main/java/org/springframework/web/context/ContextLoader.java
@@ -37,7 +37,6 @@ import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.support.PropertiesLoaderUtils;
-import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
@@ -480,7 +479,10 @@ public class ContextLoader {
 	private Class> loadInitializerClass(String className) {
 		try {
 			Class clazz = ClassUtils.forName(className, ClassUtils.getDefaultClassLoader());
-			Assert.isAssignable(ApplicationContextInitializer.class, clazz);
+			if (!ApplicationContextInitializer.class.isAssignableFrom(clazz)) {
+				throw new ApplicationContextException(
+						"Initializer class does not implement ApplicationContextInitializer interface: " + clazz);
+			}
 			return (Class>) clazz;
 		}
 		catch (ClassNotFoundException ex) {
diff --git a/spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java b/spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java
index 98c9a7cdd15..86bd732c409 100644
--- a/spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java
+++ b/spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java
@@ -816,7 +816,7 @@ final class HierarchicalUriComponents extends UriComponents {
 		private final List pathComponents;
 
 		public PathComponentComposite(List pathComponents) {
-			Assert.notNull(pathComponents);
+			Assert.notNull(pathComponents, "PathComponent List must not be null");
 			this.pathComponents = pathComponents;
 		}
 
diff --git a/spring-web/src/test/java/org/springframework/http/server/reactive/HttpHandlerAdapterSupportTests.java b/spring-web/src/test/java/org/springframework/http/server/reactive/HttpHandlerAdapterSupportTests.java
index 8f358fae7e6..896745e09a2 100644
--- a/spring-web/src/test/java/org/springframework/http/server/reactive/HttpHandlerAdapterSupportTests.java
+++ b/spring-web/src/test/java/org/springframework/http/server/reactive/HttpHandlerAdapterSupportTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,10 +41,10 @@ import static org.junit.Assert.fail;
 public class HttpHandlerAdapterSupportTests {
 
 	@Test
-	public void invalidContextPath() throws Exception {
-		testInvalidContextPath("  ", "contextPath must not be empty");
-		testInvalidContextPath("path", "contextPath must begin with '/'");
-		testInvalidContextPath("/path/", "contextPath must not end with '/'");
+	public void invalidContextPath() {
+		testInvalidContextPath("  ", "Context path must not be empty");
+		testInvalidContextPath("path", "Context path must begin with '/'");
+		testInvalidContextPath("/path/", "Context path must not end with '/'");
 	}
 
 	private void testInvalidContextPath(String contextPath, String errorMessage) {
@@ -58,7 +58,7 @@ public class HttpHandlerAdapterSupportTests {
 	}
 
 	@Test
-	public void match() throws Exception {
+	public void match() {
 		TestHttpHandler handler1 = new TestHttpHandler();
 		TestHttpHandler handler2 = new TestHttpHandler();
 		TestHttpHandler handler3 = new TestHttpHandler();
@@ -75,7 +75,7 @@ public class HttpHandlerAdapterSupportTests {
 	}
 
 	@Test
-	public void matchWithContextPathEqualToPath() throws Exception {
+	public void matchWithContextPathEqualToPath() {
 		TestHttpHandler handler1 = new TestHttpHandler();
 		TestHttpHandler handler2 = new TestHttpHandler();
 		TestHttpHandler handler3 = new TestHttpHandler();
@@ -92,7 +92,7 @@ public class HttpHandlerAdapterSupportTests {
 	}
 
 	@Test
-	public void matchWithNativeContextPath() throws Exception {
+	public void matchWithNativeContextPath() {
 		MockServerHttpRequest request = MockServerHttpRequest
 				.get("/yet/another/path")
 				.contextPath("/yet")  // contextPath in underlying request
diff --git a/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/AbstractHttpServer.java b/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/AbstractHttpServer.java
index 7fa86872226..76c3932099c 100644
--- a/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/AbstractHttpServer.java
+++ b/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/AbstractHttpServer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -80,12 +80,12 @@ public abstract class AbstractHttpServer implements HttpServer {
 
 	@Override
 	public final void afterPropertiesSet() throws Exception {
-		synchronized (this.lifecycleMonitor) {
-			Assert.isTrue(this.host != null);
-			Assert.isTrue(this.port != -1);
-			Assert.isTrue(this.httpHandler != null || this.handlerMap != null);
-			Assert.isTrue(!this.running);
+		Assert.notNull(this.host, "Host must not be null");
+		Assert.isTrue(this.port >= 0, "Port must not be a negative number");
+		Assert.isTrue(this.httpHandler != null || this.handlerMap != null, "No HttpHandler configured");
+		Assert.state(!this.running, "Cannot reconfigure while running");
 
+		synchronized (this.lifecycleMonitor) {
 			initServer();
 		}
 	}
@@ -110,7 +110,7 @@ public abstract class AbstractHttpServer implements HttpServer {
 				try {
 					startInternal();
 				}
-				catch (Exception ex) {
+				catch (Throwable ex) {
 					throw new IllegalStateException(ex);
 				}
 			}
@@ -128,7 +128,7 @@ public abstract class AbstractHttpServer implements HttpServer {
 				try {
 					stopInternal();
 				}
-				catch (Exception ex) {
+				catch (Throwable ex) {
 					throw new IllegalStateException(ex);
 				}
 				finally {
diff --git a/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/HttpServer.java b/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/HttpServer.java
index 8bc8ae12d4e..2116ad05225 100644
--- a/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/HttpServer.java
+++ b/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/HttpServer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,6 @@
 
 package org.springframework.http.server.reactive.bootstrap;
 
-
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.Lifecycle;
 import org.springframework.http.server.reactive.HttpHandler;
diff --git a/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/TomcatHttpServer.java b/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/TomcatHttpServer.java
index fc41b355723..508810fd6b4 100644
--- a/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/TomcatHttpServer.java
+++ b/spring-web/src/test/java/org/springframework/http/server/reactive/bootstrap/TomcatHttpServer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,7 +43,7 @@ public class TomcatHttpServer extends AbstractHttpServer {
 	}
 
 	public TomcatHttpServer(String baseDir, Class wsListener) {
-		Assert.notNull(baseDir);
+		Assert.notNull(baseDir, "Base dir must not be null");
 		this.baseDir = baseDir;
 		this.wsListener = wsListener;
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java
index 1a04889667b..f16e1f6b40b 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -61,7 +61,7 @@ public class MockAsyncContext implements AsyncContext {
 
 
 	public void addDispatchHandler(Runnable handler) {
-		Assert.notNull(handler);
+		Assert.notNull(handler, "Dispatch handler must not be null");
 		this.dispatchHandlers.add(handler);
 	}
 
@@ -77,7 +77,7 @@ public class MockAsyncContext implements AsyncContext {
 
 	@Override
 	public boolean hasOriginalRequestAndResponse() {
-		return (this.request instanceof MockHttpServletRequest) && (this.response instanceof MockHttpServletResponse);
+		return (this.request instanceof MockHttpServletRequest && this.response instanceof MockHttpServletResponse);
 	}
 
 	@Override
@@ -112,8 +112,8 @@ public class MockAsyncContext implements AsyncContext {
 			try {
 				listener.onComplete(new AsyncEvent(this, this.request, this.response));
 			}
-			catch (IOException e) {
-				throw new IllegalStateException("AsyncListener failure", e);
+			catch (IOException ex) {
+				throw new IllegalStateException("AsyncListener failure", ex);
 			}
 		}
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java
index 020d57866c7..b60acba5efe 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -356,12 +356,12 @@ public class MockPageContext extends PageContext {
 	}
 
 	public byte[] getContentAsByteArray() {
-		Assert.isTrue(this.response instanceof MockHttpServletResponse);
+		Assert.state(this.response instanceof MockHttpServletResponse, "MockHttpServletResponse required");
 		return ((MockHttpServletResponse) this.response).getContentAsByteArray();
 	}
 
 	public String getContentAsString() throws UnsupportedEncodingException {
-		Assert.isTrue(this.response instanceof MockHttpServletResponse);
+		Assert.state(this.response instanceof MockHttpServletResponse, "MockHttpServletResponse required");
 		return ((MockHttpServletResponse) this.response).getContentAsString();
 	}
 
diff --git a/spring-web/src/test/java/org/springframework/web/util/DefaultUriTemplateHandlerTests.java b/spring-web/src/test/java/org/springframework/web/util/DefaultUriTemplateHandlerTests.java
index 09f3700a3cb..aa30b5cac1f 100644
--- a/spring-web/src/test/java/org/springframework/web/util/DefaultUriTemplateHandlerTests.java
+++ b/spring-web/src/test/java/org/springframework/web/util/DefaultUriTemplateHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.web.util;
 
 import java.net.URI;
@@ -21,13 +22,14 @@ import java.util.Map;
 
 import org.junit.Test;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 /**
  * Unit tests for {@link DefaultUriTemplateHandler}.
  *
  * @author Rossen Stoyanchev
  */
+@SuppressWarnings("deprecation")
 public class DefaultUriTemplateHandlerTests {
 
 	private final DefaultUriTemplateHandler handler = new DefaultUriTemplateHandler();
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/HttpServletBean.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/HttpServletBean.java
index c5f3146939b..d3b91a754dd 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/HttpServletBean.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/HttpServletBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -190,7 +190,7 @@ public abstract class HttpServletBean extends HttpServlet
 	 */
 	@Override
 	public void setEnvironment(Environment environment) {
-		Assert.isInstanceOf(ConfigurableEnvironment.class, environment);
+		Assert.isInstanceOf(ConfigurableEnvironment.class, environment, "ConfigurableEnvironment required");
 		this.environment = (ConfigurableEnvironment) environment;
 	}
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java
index 671b2d323af..df5257e1f07 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -679,8 +679,8 @@ public abstract class AbstractHandlerMethodMapping extends AbstractHandlerMap
 		private final String mappingName;
 
 		public MappingRegistration(T mapping, HandlerMethod handlerMethod, List directUrls, String mappingName) {
-			Assert.notNull(mapping);
-			Assert.notNull(handlerMethod);
+			Assert.notNull(mapping, "Mapping must not be null");
+			Assert.notNull(handlerMethod, "HandlerMethod must not be null");
 			this.mapping = mapping;
 			this.handlerMethod = handlerMethod;
 			this.directUrls = (directUrls != null ? directUrls : Collections.emptyList());
@@ -745,7 +745,7 @@ public abstract class AbstractHandlerMethodMapping extends AbstractHandlerMap
 	private static class EmptyHandler {
 
 		public void handle() {
-			throw new UnsupportedOperationException("not implemented");
+			throw new UnsupportedOperationException("Not implemented");
 		}
 	}
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMapping.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMapping.java
index 71b82a74181..2b05738c89d 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMapping.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMapping.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -170,6 +170,7 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping i
 			validateHandler(handler, request);
 			return buildPathExposingHandler(handler, urlPath, urlPath, null);
 		}
+
 		// Pattern match?
 		List matchingPatterns = new ArrayList<>();
 		for (String registeredPattern : this.handlerMap.keySet()) {
@@ -182,20 +183,26 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping i
 				}
 			}
 		}
-		String bestPatternMatch = null;
+
+		String bestMatch = null;
 		Comparator patternComparator = getPathMatcher().getPatternComparator(urlPath);
 		if (!matchingPatterns.isEmpty()) {
 			Collections.sort(matchingPatterns, patternComparator);
 			if (logger.isDebugEnabled()) {
 				logger.debug("Matching patterns for request [" + urlPath + "] are " + matchingPatterns);
 			}
-			bestPatternMatch = matchingPatterns.get(0);
+			bestMatch = matchingPatterns.get(0);
 		}
-		if (bestPatternMatch != null) {
-			handler = this.handlerMap.get(bestPatternMatch);
+		if (bestMatch != null) {
+			handler = this.handlerMap.get(bestMatch);
 			if (handler == null) {
-				Assert.isTrue(bestPatternMatch.endsWith("/"));
-				handler = this.handlerMap.get(bestPatternMatch.substring(0, bestPatternMatch.length() - 1));
+				if (bestMatch.endsWith("/")) {
+					handler = this.handlerMap.get(bestMatch.substring(0, bestMatch.length() - 1));
+				}
+				if (handler == null) {
+					throw new IllegalStateException(
+							"Could not find handler for best pattern match [" + bestMatch + "]");
+				}
 			}
 			// Bean name or resolved handler?
 			if (handler instanceof String) {
@@ -203,13 +210,13 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping i
 				handler = getApplicationContext().getBean(handlerName);
 			}
 			validateHandler(handler, request);
-			String pathWithinMapping = getPathMatcher().extractPathWithinPattern(bestPatternMatch, urlPath);
+			String pathWithinMapping = getPathMatcher().extractPathWithinPattern(bestMatch, urlPath);
 
 			// There might be multiple 'best patterns', let's make sure we have the correct URI template variables
 			// for all of them
 			Map uriTemplateVariables = new LinkedHashMap<>();
 			for (String matchingPattern : matchingPatterns) {
-				if (patternComparator.compare(bestPatternMatch, matchingPattern) == 0) {
+				if (patternComparator.compare(bestMatch, matchingPattern) == 0) {
 					Map vars = getPathMatcher().extractUriTemplateVariables(matchingPattern, urlPath);
 					Map decodedVars = getUrlPathHelper().decodePathVariables(request, vars);
 					uriTemplateVariables.putAll(decodedVars);
@@ -218,8 +225,9 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping i
 			if (logger.isDebugEnabled()) {
 				logger.debug("URI Template variables for request [" + urlPath + "] are " + uriTemplateVariables);
 			}
-			return buildPathExposingHandler(handler, bestPatternMatch, pathWithinMapping, uriTemplateVariables);
+			return buildPathExposingHandler(handler, bestMatch, pathWithinMapping, uriTemplateVariables);
 		}
+
 		// No handler found...
 		return null;
 	}
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/DeferredResultMethodReturnValueHandler.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/DeferredResultMethodReturnValueHandler.java
index 87ef76c8aea..7337ef980ba 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/DeferredResultMethodReturnValueHandler.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/DeferredResultMethodReturnValueHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -92,7 +92,10 @@ public class DeferredResultMethodReturnValueHandler implements AsyncHandlerMetho
 		}
 
 		DeferredResultAdapter adapter = getAdapterFor(returnValue.getClass());
-		Assert.notNull(adapter);
+		if (adapter == null) {
+			throw new IllegalStateException(
+					"Could not find DeferredResultAdapter for return value type: " + returnValue.getClass());
+		}
 		DeferredResult result = adapter.adaptToDeferredResult(returnValue);
 		WebAsyncUtils.getAsyncManager(webRequest).startDeferredResultProcessing(result, mavContainer);
 	}
@@ -105,7 +108,7 @@ public class DeferredResultMethodReturnValueHandler implements AsyncHandlerMetho
 
 		@Override
 		public DeferredResult adaptToDeferredResult(Object returnValue) {
-			Assert.isInstanceOf(DeferredResult.class, returnValue);
+			Assert.isInstanceOf(DeferredResult.class, returnValue, "DeferredResult expected");
 			return (DeferredResult) returnValue;
 		}
 	}
@@ -118,7 +121,7 @@ public class DeferredResultMethodReturnValueHandler implements AsyncHandlerMetho
 
 		@Override
 		public DeferredResult adaptToDeferredResult(Object returnValue) {
-			Assert.isInstanceOf(ListenableFuture.class, returnValue);
+			Assert.isInstanceOf(ListenableFuture.class, returnValue, "ListenableFuture expected");
 			final DeferredResult result = new DeferredResult<>();
 			((ListenableFuture) returnValue).addCallback(new ListenableFutureCallback() {
 				@Override
@@ -142,7 +145,7 @@ public class DeferredResultMethodReturnValueHandler implements AsyncHandlerMetho
 
 		@Override
 		public DeferredResult adaptToDeferredResult(Object returnValue) {
-			Assert.isInstanceOf(CompletionStage.class, returnValue);
+			Assert.isInstanceOf(CompletionStage.class, returnValue, "CompletionStage expected");
 			final DeferredResult result = new DeferredResult<>();
 			@SuppressWarnings("unchecked")
 			CompletionStage future = (CompletionStage) returnValue;
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpHeadersReturnValueHandler.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpHeadersReturnValueHandler.java
index e3dd91d2add..b195f353a8a 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpHeadersReturnValueHandler.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpHeadersReturnValueHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -46,7 +46,7 @@ public class HttpHeadersReturnValueHandler implements HandlerMethodReturnValueHa
 
 		mavContainer.setRequestHandled(true);
 
-		Assert.isInstanceOf(HttpHeaders.class, returnValue);
+		Assert.isInstanceOf(HttpHeaders.class, returnValue, "HttpHeaders expected");
 		HttpHeaders headers = (HttpHeaders) returnValue;
 
 		if (!headers.isEmpty()) {
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java
index e2031f67e1b..547829507cf 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -240,7 +240,7 @@ public class MvcUriComponentsBuilder {
 	 * @return a UriComponents instance
 	 */
 	public static UriComponentsBuilder fromMethodCall(Object info) {
-		Assert.isInstanceOf(MethodInvocationInfo.class, info);
+		Assert.isInstanceOf(MethodInvocationInfo.class, info, "MethodInvocationInfo required");
 		MethodInvocationInfo invocationInfo = (MethodInvocationInfo) info;
 		Class controllerType = invocationInfo.getControllerType();
 		Method method = invocationInfo.getControllerMethod();
@@ -260,7 +260,7 @@ public class MvcUriComponentsBuilder {
 	 * @return a UriComponents instance
 	 */
 	public static UriComponentsBuilder fromMethodCall(UriComponentsBuilder builder, Object info) {
-		Assert.isInstanceOf(MethodInvocationInfo.class, info);
+		Assert.isInstanceOf(MethodInvocationInfo.class, info, "MethodInvocationInfo required");
 		MethodInvocationInfo invocationInfo = (MethodInvocationInfo) info;
 		Class controllerType = invocationInfo.getControllerType();
 		Method method = invocationInfo.getControllerMethod();
@@ -522,18 +522,13 @@ public class MvcUriComponentsBuilder {
 	private static WebApplicationContext getWebApplicationContext() {
 		RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
 		if (requestAttributes == null) {
-			logger.debug("No request bound to the current thread: is DispatcherSerlvet used?");
+			logger.debug("No request bound to the current thread: not in a DispatcherServlet request?");
 			return null;
 		}
 
 		HttpServletRequest request = ((ServletRequestAttributes) requestAttributes).getRequest();
-		if (request == null) {
-			logger.debug("Request bound to current thread is not an HttpServletRequest");
-			return null;
-		}
-
-		String attributeName = DispatcherServlet.WEB_APPLICATION_CONTEXT_ATTRIBUTE;
-		WebApplicationContext wac = (WebApplicationContext) request.getAttribute(attributeName);
+		WebApplicationContext wac = (WebApplicationContext)
+				request.getAttribute(DispatcherServlet.WEB_APPLICATION_CONTEXT_ATTRIBUTE);
 		if (wac == null) {
 			logger.debug("No WebApplicationContext found: not in a DispatcherServlet request?");
 			return null;
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java
index aa1f8976cb1..d15025470d7 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java
@@ -395,7 +395,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 * @param interceptors the interceptors to register
 	 */
 	public void setCallableInterceptors(List interceptors) {
-		Assert.notNull(interceptors);
+		Assert.notNull(interceptors, "CallableProcessingInterceptor List must not be null");
 		this.callableInterceptors = interceptors.toArray(new CallableProcessingInterceptor[interceptors.size()]);
 	}
 
@@ -404,7 +404,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 * @param interceptors the interceptors to register
 	 */
 	public void setDeferredResultInterceptors(List interceptors) {
-		Assert.notNull(interceptors);
+		Assert.notNull(interceptors, "DeferredResultProcessingInterceptor List must not be null");
 		this.deferredResultInterceptors = interceptors.toArray(new DeferredResultProcessingInterceptor[interceptors.size()]);
 	}
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java
index a7e391c0516..e70e16c8494 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -146,7 +146,10 @@ public class ResponseBodyEmitterReturnValueHandler implements AsyncHandlerMethod
 		ShallowEtagHeaderFilter.disableContentCaching(request);
 
 		ResponseBodyEmitterAdapter adapter = getAdapterFor(returnValue.getClass());
-		Assert.notNull(adapter);
+		if (adapter == null) {
+			throw new IllegalStateException(
+					"Could not find ResponseBodyEmitterAdapter for return value type: " + returnValue.getClass());
+		}
 		ResponseBodyEmitter emitter = adapter.adaptToEmitter(returnValue, outputMessage);
 		emitter.extendResponse(outputMessage);
 
@@ -170,7 +173,7 @@ public class ResponseBodyEmitterReturnValueHandler implements AsyncHandlerMethod
 
 		@Override
 		public ResponseBodyEmitter adaptToEmitter(Object returnValue, ServerHttpResponse response) {
-			Assert.isInstanceOf(ResponseBodyEmitter.class, returnValue);
+			Assert.isInstanceOf(ResponseBodyEmitter.class, returnValue, "ResponseBodyEmitter expected");
 			return (ResponseBodyEmitter) returnValue;
 		}
 	}
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/StreamingResponseBodyReturnValueHandler.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/StreamingResponseBodyReturnValueHandler.java
index a3b646125c6..cbbd1e62a90 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/StreamingResponseBodyReturnValueHandler.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/StreamingResponseBodyReturnValueHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -82,7 +82,7 @@ public class StreamingResponseBodyReturnValueHandler implements HandlerMethodRet
 		ServletRequest request = webRequest.getNativeRequest(ServletRequest.class);
 		ShallowEtagHeaderFilter.disableContentCaching(request);
 
-		Assert.isInstanceOf(StreamingResponseBody.class, returnValue);
+		Assert.isInstanceOf(StreamingResponseBody.class, returnValue, "StreamingResponseBody expected");
 		StreamingResponseBody streamingBody = (StreamingResponseBody) returnValue;
 
 		Callable callable = new StreamingResponseBodyTask(outputMessage.getBody(), streamingBody);
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java
index 367aed85033..f39c12a45bc 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -186,12 +186,9 @@ public class ServletUriComponentsBuilder extends UriComponentsBuilder {
 	 * Obtain current request through {@link RequestContextHolder}.
 	 */
 	protected static HttpServletRequest getCurrentRequest() {
-		RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
-		Assert.state(requestAttributes != null, "Could not find current request via RequestContextHolder");
-		Assert.isInstanceOf(ServletRequestAttributes.class, requestAttributes);
-		HttpServletRequest servletRequest = ((ServletRequestAttributes) requestAttributes).getRequest();
-		Assert.state(servletRequest != null, "Could not find current HttpServletRequest");
-		return servletRequest;
+		RequestAttributes attrs = RequestContextHolder.getRequestAttributes();
+		Assert.state(attrs instanceof ServletRequestAttributes, "No current ServletRequestAttributes");
+		return ((ServletRequestAttributes) attrs).getRequest();
 	}
 
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java
index e2e45cc927c..71a47d3b5ec 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -214,7 +214,7 @@ public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 	@Override
 	public View resolveViewName(String viewName, Locale locale) throws Exception {
 		RequestAttributes attrs = RequestContextHolder.getRequestAttributes();
-		Assert.isInstanceOf(ServletRequestAttributes.class, attrs);
+		Assert.state(attrs instanceof ServletRequestAttributes, "No current ServletRequestAttributes");
 		List requestedMediaTypes = getMediaTypes(((ServletRequestAttributes) attrs).getRequest());
 		if (requestedMediaTypes != null) {
 			List candidateViews = getCandidateViews(viewName, locale, requestedMediaTypes);
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java
index fe4a1688968..823f17b3f3d 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -125,7 +125,7 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 	 * See {@link ScriptTemplateConfigurer#setEngine(ScriptEngine)} documentation.
 	 */
 	public void setEngine(ScriptEngine engine) {
-		Assert.isInstanceOf(Invocable.class, engine);
+		Assert.isInstanceOf(Invocable.class, engine, "ScriptEngine must implement Invocable");
 		this.engine = engine;
 	}
 
diff --git a/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterTests.java b/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterTests.java
index 44a22bb6cab..3709a5e8ed5 100644
--- a/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterTests.java
+++ b/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,14 +22,12 @@ import org.junit.Before;
 import org.junit.Test;
 import org.mockito.ArgumentCaptor;
 import org.mockito.Mock;
-import static org.mockito.Mockito.*;
-
 import org.mockito.MockitoAnnotations;
 
 import org.springframework.http.MediaType;
-import org.springframework.util.Assert;
 
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
 
 /**
  * Unit tests for {@link ResponseBodyEmitter}.
@@ -166,7 +164,7 @@ public class ResponseBodyEmitterTests {
 		verify(this.handler).onTimeout(captor.capture());
 		verify(this.handler).onCompletion(any());
 
-		Assert.notNull(captor.getValue());
+		assertNotNull(captor.getValue());
 		captor.getValue().run();
 		verify(runnable).run();
 	}
@@ -182,7 +180,7 @@ public class ResponseBodyEmitterTests {
 		Runnable runnable = mock(Runnable.class);
 		this.emitter.onTimeout(runnable);
 
-		Assert.notNull(captor.getValue());
+		assertNotNull(captor.getValue());
 		captor.getValue().run();
 		verify(runnable).run();
 	}
@@ -197,7 +195,7 @@ public class ResponseBodyEmitterTests {
 		verify(this.handler).onTimeout(any());
 		verify(this.handler).onCompletion(captor.capture());
 
-		Assert.notNull(captor.getValue());
+		assertNotNull(captor.getValue());
 		captor.getValue().run();
 		verify(runnable).run();
 	}
@@ -213,7 +211,7 @@ public class ResponseBodyEmitterTests {
 		Runnable runnable = mock(Runnable.class);
 		this.emitter.onCompletion(runnable);
 
-		Assert.notNull(captor.getValue());
+		assertNotNull(captor.getValue());
 		captor.getValue().run();
 		verify(runnable).run();
 	}
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/AbstractWebSocketHandlerRegistration.java b/spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/AbstractWebSocketHandlerRegistration.java
index 20db2a831fa..8b9fb9512c8 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/AbstractWebSocketHandlerRegistration.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/AbstractWebSocketHandlerRegistration.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,8 +28,8 @@ import org.springframework.util.ObjectUtils;
 import org.springframework.web.socket.WebSocketHandler;
 import org.springframework.web.socket.server.HandshakeHandler;
 import org.springframework.web.socket.server.HandshakeInterceptor;
-import org.springframework.web.socket.server.support.OriginHandshakeInterceptor;
 import org.springframework.web.socket.server.support.DefaultHandshakeHandler;
+import org.springframework.web.socket.server.support.OriginHandshakeInterceptor;
 import org.springframework.web.socket.sockjs.SockJsService;
 import org.springframework.web.socket.sockjs.transport.handler.WebSocketTransportHandler;
 
@@ -45,7 +45,7 @@ public abstract class AbstractWebSocketHandlerRegistration implements WebSock
 
 	private final TaskScheduler sockJsTaskScheduler;
 
-	private MultiValueMap handlerMap = new LinkedMultiValueMap<>();
+	private final MultiValueMap handlerMap = new LinkedMultiValueMap<>();
 
 	private HandshakeHandler handshakeHandler;
 
@@ -63,8 +63,8 @@ public abstract class AbstractWebSocketHandlerRegistration implements WebSock
 
 	@Override
 	public WebSocketHandlerRegistration addHandler(WebSocketHandler handler, String... paths) {
-		Assert.notNull(handler);
-		Assert.notEmpty(paths);
+		Assert.notNull(handler, "WebSocketHandler must not be null");
+		Assert.notEmpty(paths, "Paths must not be empty");
 		this.handlerMap.put(handler, Arrays.asList(paths));
 		return this;
 	}
@@ -108,13 +108,14 @@ public abstract class AbstractWebSocketHandlerRegistration implements WebSock
 			this.sockJsServiceRegistration.setTransportHandlerOverrides(transportHandler);
 		}
 		if (!this.allowedOrigins.isEmpty()) {
-			this.sockJsServiceRegistration.setAllowedOrigins(this.allowedOrigins.toArray(new String[this.allowedOrigins.size()]));
+			this.sockJsServiceRegistration.setAllowedOrigins(
+					this.allowedOrigins.toArray(new String[this.allowedOrigins.size()]));
 		}
 		return this.sockJsServiceRegistration;
 	}
 
 	protected HandshakeInterceptor[] getInterceptors() {
-		List interceptors = new ArrayList<>();
+		List interceptors = new ArrayList<>(this.interceptors.size() + 1);
 		interceptors.addAll(this.interceptors);
 		interceptors.add(new OriginHandshakeInterceptor(this.allowedOrigins));
 		return interceptors.toArray(new HandshakeInterceptor[interceptors.size()]);
@@ -126,7 +127,7 @@ public abstract class AbstractWebSocketHandlerRegistration implements WebSock
 			SockJsService sockJsService = this.sockJsServiceRegistration.getSockJsService();
 			for (WebSocketHandler wsHandler : this.handlerMap.keySet()) {
 				for (String path : this.handlerMap.get(wsHandler)) {
-					String pathPattern = path.endsWith("/") ? path + "**" : path + "/**";
+					String pathPattern = (path.endsWith("/") ? path + "**" : path + "/**");
 					addSockJsServiceMapping(mappings, sockJsService, wsHandler, pathPattern);
 				}
 			}
@@ -145,9 +146,10 @@ public abstract class AbstractWebSocketHandlerRegistration implements WebSock
 	}
 
 	private HandshakeHandler getOrCreateHandshakeHandler() {
-		return (this.handshakeHandler != null) ? this.handshakeHandler : new DefaultHandshakeHandler();
+		return (this.handshakeHandler != null ? this.handshakeHandler : new DefaultHandshakeHandler());
 	}
 
+
 	protected abstract M createMappings();
 
 	protected abstract void addSockJsServiceMapping(M mappings, SockJsService sockJsService,
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java b/spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java
index 6889a6fbe30..452a97c5ad4 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -60,6 +60,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		return Ordered.LOWEST_PRECEDENCE;
 	}
 
+
 	// SmartApplicationListener methods
 
 	@Override
@@ -69,7 +70,6 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 	@Override
 	public void onApplicationEvent(ApplicationEvent event) {
-
 		AbstractSubProtocolEvent subProtocolEvent = (AbstractSubProtocolEvent) event;
 		Message message = subProtocolEvent.getMessage();
 		SimpMessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, SimpMessageHeaderAccessor.class);
@@ -129,6 +129,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		return true;
 	}
 
+
 	// SimpUserRegistry methods
 
 	@Override
@@ -169,12 +170,10 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 		private final String name;
 
-		private final Map userSessions =
-				new ConcurrentHashMap<>(1);
-
+		private final Map userSessions = new ConcurrentHashMap<>(1);
 
 		public LocalSimpUser(String userName) {
-			Assert.notNull(userName);
+			Assert.notNull(userName, "User name must not be null");
 			this.name = userName;
 		}
 
@@ -208,13 +207,8 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 		@Override
 		public boolean equals(Object other) {
-			if (this == other) {
-				return true;
-			}
-			if (other == null || !(other instanceof SimpUser)) {
-				return false;
-			}
-			return this.name.equals(((SimpUser) other).getName());
+			return (this == other ||
+					(other instanceof SimpUser && this.name.equals(((SimpUser) other).getName())));
 		}
 
 		@Override
@@ -228,6 +222,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		}
 	}
 
+
 	private static class LocalSimpSession implements SimpSession {
 
 		private final String id;
@@ -236,10 +231,9 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 		private final Map subscriptions = new ConcurrentHashMap<>(4);
 
-
 		public LocalSimpSession(String id, LocalSimpUser user) {
-			Assert.notNull(id);
-			Assert.notNull(user);
+			Assert.notNull(id, "Id must not be null");
+			Assert.notNull(user, "User must not be null");
 			this.id = id;
 			this.user = user;
 		}
@@ -268,19 +262,14 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		}
 
 		@Override
-		public int hashCode() {
-			return this.id.hashCode();
+		public boolean equals(Object other) {
+			return (this == other ||
+					(other instanceof SimpSubscription && this.id.equals(((SimpSubscription) other).getId())));
 		}
 
 		@Override
-		public boolean equals(Object other) {
-			if (this == other) {
-				return true;
-			}
-			if (other == null || !(other instanceof SimpSubscription)) {
-				return false;
-			}
-			return this.id.equals(((SimpSubscription) other).getId());
+		public int hashCode() {
+			return this.id.hashCode();
 		}
 
 		@Override
@@ -289,6 +278,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		}
 	}
 
+
 	private static class LocalSimpSubscription implements SimpSubscription {
 
 		private final String id;
@@ -297,11 +287,10 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 		private final String destination;
 
-
 		public LocalSimpSubscription(String id, String destination, LocalSimpSession session) {
-			Assert.notNull(id);
-			Assert.hasText(destination);
-			Assert.notNull(session);
+			Assert.notNull(id, "Id must not be null");
+			Assert.hasText(destination, "Destination must not be empty");
+			Assert.notNull(session, "Session must not be null");
 			this.id = id;
 			this.destination = destination;
 			this.session = session;
@@ -322,22 +311,22 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 			return this.destination;
 		}
 
-		@Override
-		public int hashCode() {
-			return 31 * this.id.hashCode() + getSession().hashCode();
-		}
-
 		@Override
 		public boolean equals(Object other) {
 			if (this == other) {
 				return true;
 			}
-			if (other == null || !(other instanceof SimpSubscription)) {
+			if (!(other instanceof SimpSubscription)) {
 				return false;
 			}
 			SimpSubscription otherSubscription = (SimpSubscription) other;
-			return (getSession().getId().equals(otherSubscription.getSession().getId()) &&
-					this.id.equals(otherSubscription.getId()));
+			return (this.id.equals(otherSubscription.getId()) &&
+					getSession().getId().equals(otherSubscription.getSession().getId()));
+		}
+
+		@Override
+		public int hashCode() {
+			return this.id.hashCode() * 31 + getSession().getId().hashCode();
 		}
 
 		@Override
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java b/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java
index 9ab8a331796..45963cd830b 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -174,10 +174,10 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Serv
 			String selectedProtocol, List selectedExtensions, Principal user,
 			WebSocketHandler wsHandler, Map attributes) throws HandshakeFailureException {
 
-		Assert.isInstanceOf(ServletServerHttpRequest.class, request);
+		Assert.isInstanceOf(ServletServerHttpRequest.class, request, "ServletServerHttpRequest required");
 		HttpServletRequest servletRequest = ((ServletServerHttpRequest) request).getServletRequest();
 
-		Assert.isInstanceOf(ServletServerHttpResponse.class, response);
+		Assert.isInstanceOf(ServletServerHttpResponse.class, response, "ServletServerHttpResponse required");
 		HttpServletResponse servletResponse = ((ServletServerHttpResponse) response).getServletResponse();
 
 		Assert.isTrue(this.factoryAdapter.getFactory().isUpgradeRequest(servletRequest, servletResponse),
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/server/standard/AbstractStandardUpgradeStrategy.java b/spring-websocket/src/main/java/org/springframework/web/socket/server/standard/AbstractStandardUpgradeStrategy.java
index e7f2c841633..38a52fdc5cb 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/server/standard/AbstractStandardUpgradeStrategy.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/server/standard/AbstractStandardUpgradeStrategy.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -71,12 +71,12 @@ public abstract class AbstractStandardUpgradeStrategy implements RequestUpgradeS
 	}
 
 	protected final HttpServletRequest getHttpServletRequest(ServerHttpRequest request) {
-		Assert.isTrue(request instanceof ServletServerHttpRequest);
+		Assert.isTrue(request instanceof ServletServerHttpRequest, "ServletServerHttpRequest required");
 		return ((ServletServerHttpRequest) request).getServletRequest();
 	}
 
 	protected final HttpServletResponse getHttpServletResponse(ServerHttpResponse response) {
-		Assert.isTrue(response instanceof ServletServerHttpResponse);
+		Assert.isTrue(response instanceof ServletServerHttpResponse, "ServletServerHttpResponse required");
 		return ((ServletServerHttpResponse) response).getServletResponse();
 	}
 
@@ -92,8 +92,8 @@ public abstract class AbstractStandardUpgradeStrategy implements RequestUpgradeS
 
 	protected List getInstalledExtensions(WebSocketContainer container) {
 		List result = new ArrayList<>();
-		for (Extension ext : container.getInstalledExtensions()) {
-			result.add(new StandardToWebSocketExtensionAdapter(ext));
+		for (Extension extension : container.getInstalledExtensions()) {
+			result.add(new StandardToWebSocketExtensionAdapter(extension));
 		}
 		return result;
 	}
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransport.java b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransport.java
index e52c2cae6f3..75e7c514b76 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransport.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransport.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -81,7 +81,7 @@ public class RestTemplateXhrTransport extends AbstractXhrTransport {
 	 * time the transports connects.
 	 */
 	public void setTaskExecutor(TaskExecutor taskExecutor) {
-		Assert.notNull(this.taskExecutor);
+		Assert.notNull(taskExecutor, "TaskExecutor must not be null");
 		this.taskExecutor = taskExecutor;
 	}
 
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/WebSocketTransport.java b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/WebSocketTransport.java
index 30fbd071c99..227f4fae3c4 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/WebSocketTransport.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/WebSocketTransport.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package org.springframework.web.socket.sockjs.client;
 import java.net.URI;
 import java.util.Collections;
 import java.util.List;
-import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -82,7 +82,7 @@ public class WebSocketTransport implements Transport, Lifecycle {
 		URI url = request.getTransportUrl();
 		WebSocketHttpHeaders headers = new WebSocketHttpHeaders(request.getHandshakeHeaders());
 		if (logger.isDebugEnabled()) {
-			logger.debug("Starting WebSocket session url=" + url);
+			logger.debug("Starting WebSocket session on " + url);
 		}
 		this.webSocketClient.doHandshake(handler, headers, url).addCallback(
 				new ListenableFutureCallback() {
@@ -144,16 +144,16 @@ public class WebSocketTransport implements Transport, Lifecycle {
 
 		private final WebSocketClientSockJsSession sockJsSession;
 
-		private final AtomicInteger connectCount = new AtomicInteger(0);
+		private final AtomicBoolean connected = new AtomicBoolean(false);
 
 		public ClientSockJsWebSocketHandler(WebSocketClientSockJsSession session) {
-			Assert.notNull(session);
+			Assert.notNull(session, "Session must not be null");
 			this.sockJsSession = session;
 		}
 
 		@Override
 		public void afterConnectionEstablished(WebSocketSession webSocketSession) throws Exception {
-			Assert.isTrue(this.connectCount.compareAndSet(0, 1));
+			Assert.state(this.connected.compareAndSet(false, true), "Already connected");
 			this.sockJsSession.initializeDelegateSession(webSocketSession);
 		}
 
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractSockJsSession.java b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractSockJsSession.java
index 4b00a038f8e..dc89abea2b7 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractSockJsSession.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractSockJsSession.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -162,7 +162,7 @@ public abstract class AbstractSockJsSession implements SockJsSession {
 
 	public final void sendMessage(WebSocketMessage message) throws IOException {
 		Assert.state(!isClosed(), "Cannot send a message when session is closed");
-		Assert.isInstanceOf(TextMessage.class, message, "SockJS supports text messages only: " + message);
+		Assert.isInstanceOf(TextMessage.class, message, "SockJS supports text messages only");
 		sendMessageInternal(((TextMessage) message).getPayload());
 	}
 
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/StreamingSockJsSession.java b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/StreamingSockJsSession.java
index cc308b0ec72..2eda43e60ad 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/StreamingSockJsSession.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/StreamingSockJsSession.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,7 +58,7 @@ public abstract class StreamingSockJsSession extends AbstractHttpSockJsSession {
 			boolean initialRequest) throws IOException {
 
 		byte[] prelude = getPrelude(request);
-		Assert.notNull(prelude);
+		Assert.state(prelude != null, "Prelude expected");
 		response.getBody().write(prelude);
 		response.flush();