Nullability fine-tuning around declaration inconsistencies

Issue: SPR-15720
Issue: SPR-15792

spring-aop/src/main/java/org/springframework/aop/Advisor.java

@@ -31,9 +31,18 @@ import org.aopalliance.aop.Advice;
  * implemented using interception.
  *
  * @author Rod Johnson
+ * @author Juergen Hoeller
  */
 public interface Advisor {
 
+	/**
+	 * Common placeholder for an empty {@code Advice} to be returned from
+	 * {@link #getAdvice()} if no proper advice has been configured (yet).
+	 * @since 5.0
+	 */
+	Advice EMPTY_ADVICE = new Advice() {};
+
+
 	/**
 	 * Return the advice part of this aspect. An advice may be an
 	 * interceptor, a before advice, a throws advice, etc.

spring-aop/src/main/java/org/springframework/aop/aspectj/AspectJPointcutAdvisor.java

@@ -23,7 +23,6 @@ import org.springframework.aop.PointcutAdvisor;
 import org.springframework.core.Ordered;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
-import org.springframework.util.ObjectUtils;
 
 /**
  * AspectJPointcutAdvisor that adapts an {@link AbstractAspectJAdvice}
@@ -53,11 +52,11 @@ public class AspectJPointcutAdvisor implements PointcutAdvisor, Ordered {
 		this.pointcut = advice.buildSafePointcut();
 	}
 
+
 	public void setOrder(int order) {
 		this.order = order;
 	}
 
-
 	@Override
 	public boolean isPerInstance() {
 		return true;
@@ -93,12 +92,12 @@ public class AspectJPointcutAdvisor implements PointcutAdvisor, Ordered {
 			return false;
 		}
 		AspectJPointcutAdvisor otherAdvisor = (AspectJPointcutAdvisor) other;
-		return (ObjectUtils.nullSafeEquals(this.advice, otherAdvisor.advice));
+		return this.advice.equals(otherAdvisor.advice);
 	}
 
 	@Override
 	public int hashCode() {
-		return AspectJPointcutAdvisor.class.hashCode();
+		return AspectJPointcutAdvisor.class.hashCode() * 29 + this.advice.hashCode();
 	}
 
 }

spring-aop/src/main/java/org/springframework/aop/config/AdvisorComponentDefinition.java

@@ -39,11 +39,11 @@ public class AdvisorComponentDefinition extends AbstractComponentDefinition {
 
 	private final BeanDefinition advisorDefinition;
 
-	private String description;
+	private final String description;
 
-	private BeanReference[] beanReferences;
+	private final BeanReference[] beanReferences;
 
-	private BeanDefinition[] beanDefinitions;
+	private final BeanDefinition[] beanDefinitions;
 
 
 	public AdvisorComponentDefinition(String advisorBeanName, BeanDefinition advisorDefinition) {
@@ -57,11 +57,7 @@ public class AdvisorComponentDefinition extends AbstractComponentDefinition {
 		Assert.notNull(advisorDefinition, "'advisorDefinition' must not be null");
 		this.advisorBeanName = advisorBeanName;
 		this.advisorDefinition = advisorDefinition;
-		unwrapDefinitions(advisorDefinition, pointcutDefinition);
-	}
-
 
-	private void unwrapDefinitions(BeanDefinition advisorDefinition, @Nullable BeanDefinition pointcutDefinition) {
 		MutablePropertyValues pvs = advisorDefinition.getPropertyValues();
 		BeanReference adviceReference = (BeanReference) pvs.get("adviceBeanName");
 		Assert.state(adviceReference != null, "Missing 'adviceBeanName' property");

spring-aop/src/main/java/org/springframework/aop/config/SimpleBeanFactoryAwareAspectInstanceFactory.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.
@@ -21,6 +21,8 @@ import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.Ordered;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 
@@ -34,8 +36,10 @@ import org.springframework.util.StringUtils;
  */
 public class SimpleBeanFactoryAwareAspectInstanceFactory implements AspectInstanceFactory, BeanFactoryAware {
 
+	@Nullable
 	private String aspectBeanName;
 
+	@Nullable
 	private BeanFactory beanFactory;
 
 
@@ -50,9 +54,7 @@ public class SimpleBeanFactoryAwareAspectInstanceFactory implements AspectInstan
 	@Override
 	public void setBeanFactory(BeanFactory beanFactory) {
 		this.beanFactory = beanFactory;
-		if (!StringUtils.hasText(this.aspectBeanName)) {
-			throw new IllegalArgumentException("'aspectBeanName' is required");
-		}
+		Assert.notNull(this.aspectBeanName, "'aspectBeanName' is required");
 	}
 
 
@@ -62,6 +64,8 @@ public class SimpleBeanFactoryAwareAspectInstanceFactory implements AspectInstan
 	 */
 	@Override
 	public Object getAspectInstance() {
+		Assert.state(this.beanFactory != null, "No BeanFactory set");
+		Assert.state(this.aspectBeanName != null, "No 'aspectBeanName' set");
 		return this.beanFactory.getBean(this.aspectBeanName);
 	}
 
@@ -77,7 +81,8 @@ public class SimpleBeanFactoryAwareAspectInstanceFactory implements AspectInstan
 
 	@Override
 	public int getOrder() {
-		if (this.beanFactory.isSingleton(this.aspectBeanName) &&
+		if (this.beanFactory != null && this.aspectBeanName != null &&
+				this.beanFactory.isSingleton(this.aspectBeanName) &&
 				this.beanFactory.isTypeMatch(this.aspectBeanName, Ordered.class)) {
 			return ((Ordered) this.beanFactory.getBean(this.aspectBeanName)).getOrder();
 		}

spring-aop/src/main/java/org/springframework/aop/framework/AbstractAdvisingBeanPostProcessor.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.
@@ -22,6 +22,7 @@ import java.util.concurrent.ConcurrentHashMap;
 import org.springframework.aop.Advisor;
 import org.springframework.aop.support.AopUtils;
 import org.springframework.beans.factory.config.BeanPostProcessor;
+import org.springframework.lang.Nullable;
 
 /**
  * Base class for {@link BeanPostProcessor} implementations that apply a
@@ -33,6 +34,7 @@ import org.springframework.beans.factory.config.BeanPostProcessor;
 @SuppressWarnings("serial")
 public abstract class AbstractAdvisingBeanPostProcessor extends ProxyProcessorSupport implements BeanPostProcessor {
 
+	@Nullable
 	protected Advisor advisor;
 
 	protected boolean beforeExistingAdvisors = false;
@@ -61,7 +63,7 @@ public abstract class AbstractAdvisingBeanPostProcessor extends ProxyProcessorSu
 
 	@Override
 	public Object postProcessAfterInitialization(Object bean, String beanName) {
-		if (bean instanceof AopInfrastructureBean) {
+		if (bean instanceof AopInfrastructureBean || this.advisor == null) {
 			// Ignore AOP infrastructure such as scoped proxies.
 			return bean;
 		}
@@ -125,6 +127,9 @@ public abstract class AbstractAdvisingBeanPostProcessor extends ProxyProcessorSu
 		if (eligible != null) {
 			return eligible;
 		}
+		if (this.advisor == null) {
+			return false;
+		}
 		eligible = AopUtils.canApply(this.advisor, targetClass);
 		this.eligibleBeans.put(targetClass, eligible);
 		return eligible;

spring-aop/src/main/java/org/springframework/aop/framework/AdvisedSupport.java

@@ -107,7 +107,7 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 	 * No-arg constructor for use as a JavaBean.
 	 */
 	public AdvisedSupport() {
-		initMethodCache();
+		this.methodCache = new ConcurrentHashMap<>(32);
 	}
 
 	/**
@@ -119,13 +119,6 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 		setInterfaces(interfaces);
 	}
 
-	/**
-	 * Initialize the method cache.
-	 */
-	private void initMethodCache() {
-		this.methodCache = new ConcurrentHashMap<>(32);
-	}
-
 
 	/**
 	 * Set the given object as target.
@@ -558,7 +551,7 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 		ois.defaultReadObject();
 
 		// Initialize transient fields.
-		initMethodCache();
+		this.methodCache = new ConcurrentHashMap<>(32);
 	}
 
 

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java

@@ -25,6 +25,7 @@ import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Generic auto proxy creator that builds AOP proxies for specific beans
@@ -48,6 +49,7 @@ import org.springframework.lang.Nullable;
 @SuppressWarnings("serial")
 public abstract class AbstractAdvisorAutoProxyCreator extends AbstractAutoProxyCreator {
 
+	@Nullable
 	private BeanFactoryAdvisorRetrievalHelper advisorRetrievalHelper;
 
 
@@ -101,6 +103,7 @@ public abstract class AbstractAdvisorAutoProxyCreator extends AbstractAutoProxyC
 	 * @return the List of candidate Advisors
 	 */
 	protected List<Advisor> findCandidateAdvisors() {
+		Assert.state(this.advisorRetrievalHelper != null, "No BeanFactoryAdvisorRetrievalHelper available");
 		return this.advisorRetrievalHelper.findAdvisorBeans();
 	}
 

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAutoProxyCreator.java

@@ -203,7 +203,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	}
 
 	@Override
-	public void setBeanFactory(@Nullable BeanFactory beanFactory) {
+	public void setBeanFactory(BeanFactory beanFactory) {
 		this.beanFactory = beanFactory;
 	}
 
@@ -241,10 +241,10 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	}
 
 	@Override
-	public Object postProcessBeforeInstantiation(Class<?> beanClass, @Nullable String beanName) throws BeansException {
+	public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
 		Object cacheKey = getCacheKey(beanClass, beanName);
 
-		if (beanName == null || !this.targetSourcedBeans.contains(beanName)) {
+		if (!StringUtils.hasLength(beanName) || !this.targetSourcedBeans.contains(beanName)) {
 			if (this.advisedBeans.containsKey(cacheKey)) {
 				return null;
 			}
@@ -257,15 +257,15 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 		// Create proxy here if we have a custom TargetSource.
 		// Suppresses unnecessary default instantiation of the target bean:
 		// The TargetSource will handle target instances in a custom fashion.
-		if (beanName != null) {
-			TargetSource targetSource = getCustomTargetSource(beanClass, beanName);
-			if (targetSource != null) {
+		TargetSource targetSource = getCustomTargetSource(beanClass, beanName);
+		if (targetSource != null) {
+			if (StringUtils.hasLength(beanName)) {
 				this.targetSourcedBeans.add(beanName);
-				Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(beanClass, beanName, targetSource);
-				Object proxy = createProxy(beanClass, beanName, specificInterceptors, targetSource);
-				this.proxyTypes.put(cacheKey, proxy.getClass());
-				return proxy;
 			}
+			Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(beanClass, beanName, targetSource);
+			Object proxy = createProxy(beanClass, beanName, specificInterceptors, targetSource);
+			this.proxyTypes.put(cacheKey, proxy.getClass());
+			return proxy;
 		}
 
 		return null;
@@ -333,8 +333,8 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @param cacheKey the cache key for metadata access
 	 * @return a proxy wrapping the bean, or the raw bean instance as-is
 	 */
-	protected Object wrapIfNecessary(Object bean, @Nullable String beanName, Object cacheKey) {
-		if (beanName != null && this.targetSourcedBeans.contains(beanName)) {
+	protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
+		if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) {
 			return bean;
 		}
 		if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {
@@ -391,7 +391,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @param beanName the name of the bean
 	 * @return whether to skip the given bean
 	 */
-	protected boolean shouldSkip(Class<?> beanClass, @Nullable String beanName) {
+	protected boolean shouldSkip(Class<?> beanClass, String beanName) {
 		return false;
 	}
 
@@ -582,8 +582,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @see #PROXY_WITHOUT_ADDITIONAL_INTERCEPTORS
 	 */
 	@Nullable
-	protected abstract Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass,
-			@Nullable String beanName, @Nullable TargetSource customTargetSource)
-			throws BeansException;
+	protected abstract Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass, String beanName,
+			@Nullable TargetSource customTargetSource) throws BeansException;
 
 }

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/BeanNameAutoProxyCreator.java

@@ -76,7 +76,9 @@ public class BeanNameAutoProxyCreator extends AbstractAutoProxyCreator {
 	 */
 	@Override
 	@Nullable
-	protected Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass, String beanName, @Nullable TargetSource targetSource) {
+	protected Object[] getAdvicesAndAdvisorsForBean(
+			Class<?> beanClass, String beanName, @Nullable TargetSource targetSource) {
+
 		if (this.beanNames != null) {
 			for (String mappedName : this.beanNames) {
 				if (FactoryBean.class.isAssignableFrom(beanClass)) {

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/InfrastructureAdvisorAutoProxyCreator.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.
@@ -18,6 +18,7 @@ package org.springframework.aop.framework.autoproxy;
 
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.lang.Nullable;
 
 /**
  * Auto-proxy creator that considers infrastructure Advisor beans only,
@@ -29,6 +30,7 @@ import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 @SuppressWarnings("serial")
 public class InfrastructureAdvisorAutoProxyCreator extends AbstractAdvisorAutoProxyCreator {
 
+	@Nullable
 	private ConfigurableListableBeanFactory beanFactory;
 
 
@@ -40,7 +42,7 @@ public class InfrastructureAdvisorAutoProxyCreator extends AbstractAdvisorAutoPr
 
 	@Override
 	protected boolean isEligibleAdvisorBean(String beanName) {
-		return (this.beanFactory.containsBeanDefinition(beanName) &&
+		return (this.beanFactory != null && this.beanFactory.containsBeanDefinition(beanName) &&
 				this.beanFactory.getBeanDefinition(beanName).getRole() == BeanDefinition.ROLE_INFRASTRUCTURE);
 	}
 

spring-aop/src/main/java/org/springframework/aop/support/AbstractExpressionPointcut.java

@@ -89,6 +89,7 @@ public abstract class AbstractExpressionPointcut implements ExpressionPointcut,
 	 * Return this pointcut's expression.
 	 */
 	@Override
+	@Nullable
 	public String getExpression() {
 		return this.expression;
 	}

spring-aop/src/main/java/org/springframework/aop/support/AbstractGenericPointcutAdvisor.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.
@@ -19,7 +19,8 @@ package org.springframework.aop.support;
 import org.aopalliance.aop.Advice;
 
 /**
- * Abstract generic PointcutAdvisor that allows for any Advice to be configured.
+ * Abstract generic {@link org.springframework.aop.PointcutAdvisor}
+ * that allows for any {@link Advice} to be configured.
  *
  * @author Juergen Hoeller
  * @since 2.0
@@ -29,7 +30,7 @@ import org.aopalliance.aop.Advice;
 @SuppressWarnings("serial")
 public abstract class AbstractGenericPointcutAdvisor extends AbstractPointcutAdvisor {
 
-	private Advice advice;
+	private Advice advice = EMPTY_ADVICE;
 
 
 	/**

spring-aop/src/main/java/org/springframework/aop/support/DelegatingIntroductionInterceptor.java

@@ -57,6 +57,7 @@ public class DelegatingIntroductionInterceptor extends IntroductionInfoSupport
 	 * Object that actually implements the interfaces.
 	 * May be "this" if a subclass implements the introduced interfaces.
 	 */
+	@Nullable
 	private Object delegate;
 
 

spring-aop/src/main/java/org/springframework/aop/support/StaticMethodMatcherPointcutAdvisor.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.
@@ -38,7 +38,7 @@ public abstract class StaticMethodMatcherPointcutAdvisor extends StaticMethodMat
 
 	private int order = Integer.MAX_VALUE;
 
-	private Advice advice;
+	private Advice advice = EMPTY_ADVICE;
 
 
 	/**

spring-beans/src/main/java/org/springframework/beans/AbstractNestablePropertyAccessor.java

@@ -578,6 +578,7 @@ public abstract class AbstractNestablePropertyAccessor extends AbstractPropertyA
 			@Nullable Object newValue, @Nullable Class<?> requiredType, @Nullable TypeDescriptor td)
 			throws TypeMismatchException {
 
+		Assert.state(this.typeConverterDelegate != null, "No TypeConverterDelegate");
 		try {
 			return this.typeConverterDelegate.convertIfNecessary(propertyName, oldValue, newValue, requiredType, td);
 		}

spring-beans/src/main/java/org/springframework/beans/BeanInstantiationException.java

@@ -33,8 +33,10 @@ public class BeanInstantiationException extends FatalBeanException {
 
 	private Class<?> beanClass;
 
+	@Nullable
 	private Constructor<?> constructor;
 
+	@Nullable
 	private Method constructingMethod;
 
 

spring-beans/src/main/java/org/springframework/beans/DirectFieldAccessor.java

@@ -22,6 +22,7 @@ import java.util.Map;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -134,7 +135,7 @@ public class DirectFieldAccessor extends AbstractNestablePropertyAccessor {
 		}
 
 		@Override
-		public void setValue(Object value) throws Exception {
+		public void setValue(@Nullable Object value) throws Exception {
 			try {
 				ReflectionUtils.makeAccessible(this.field);
 				this.field.set(getWrappedInstance(), value);

spring-beans/src/main/java/org/springframework/beans/TypeConverterSupport.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.
@@ -22,6 +22,7 @@ import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionException;
 import org.springframework.core.convert.ConverterNotFoundException;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Base implementation of the {@link TypeConverter} interface, using a package-private delegate.
@@ -33,6 +34,7 @@ import org.springframework.lang.Nullable;
  */
 public abstract class TypeConverterSupport extends PropertyEditorRegistrySupport implements TypeConverter {
 
+	@Nullable
 	TypeConverterDelegate typeConverterDelegate;
 
 
@@ -59,6 +61,7 @@ public abstract class TypeConverterSupport extends PropertyEditorRegistrySupport
 	private <T> T doConvert(@Nullable Object value,@Nullable Class<T> requiredType,
 			@Nullable MethodParameter methodParam, @Nullable Field field) throws TypeMismatchException {
 
+		Assert.state(this.typeConverterDelegate != null, "No TypeConverterDelegate");
 		try {
 			if (field != null) {
 				return this.typeConverterDelegate.convertIfNecessary(value, requiredType, field);

spring-beans/src/main/java/org/springframework/beans/factory/NoUniqueBeanDefinitionException.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 @@ public class NoUniqueBeanDefinitionException extends NoSuchBeanDefinitionExcepti
 
 	private int numberOfBeansFound;
 
+	@Nullable
 	private Collection<String> beanNamesFound;
 
 

spring-beans/src/main/java/org/springframework/beans/factory/annotation/AnnotatedGenericBeanDefinition.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.
@@ -20,6 +20,7 @@ import org.springframework.beans.factory.support.GenericBeanDefinition;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.core.type.MethodMetadata;
 import org.springframework.core.type.StandardAnnotationMetadata;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -44,6 +45,7 @@ public class AnnotatedGenericBeanDefinition extends GenericBeanDefinition implem
 
 	private final AnnotationMetadata metadata;
 
+	@Nullable
 	private MethodMetadata factoryMethodMetadata;
 
 
@@ -98,6 +100,7 @@ public class AnnotatedGenericBeanDefinition extends GenericBeanDefinition implem
 	}
 
 	@Override
+	@Nullable
 	public final MethodMetadata getFactoryMethodMetadata() {
 		return this.factoryMethodMetadata;
 	}

spring-beans/src/main/java/org/springframework/beans/factory/annotation/RequiredAnnotationBeanPostProcessor.java

@@ -89,6 +89,7 @@ public class RequiredAnnotationBeanPostProcessor extends InstantiationAwareBeanP
 
 	private int order = Ordered.LOWEST_PRECEDENCE - 1;
 
+	@Nullable
 	private ConfigurableListableBeanFactory beanFactory;
 
 	/**

spring-beans/src/main/java/org/springframework/beans/factory/config/PropertiesFactoryBean.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.
@@ -22,6 +22,7 @@ import java.util.Properties;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.core.io.support.PropertiesLoaderSupport;
+import org.springframework.lang.Nullable;
 
 /**
  * Allows for making a properties file from a classpath location available
@@ -47,6 +48,7 @@ public class PropertiesFactoryBean extends PropertiesLoaderSupport
 
 	private boolean singleton = true;
 
+	@Nullable
 	private Properties singletonInstance;
 
 

spring-beans/src/main/java/org/springframework/beans/factory/parsing/BeanComponentDefinition.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.
@@ -47,8 +47,7 @@ public class BeanComponentDefinition extends BeanDefinitionHolder implements Com
 	 * @param beanName the name of the bean
 	 */
 	public BeanComponentDefinition(BeanDefinition beanDefinition, String beanName) {
-		super(beanDefinition, beanName);
-		findInnerBeanDefinitionsAndBeanReferences(beanDefinition);
+		this(new BeanDefinitionHolder(beanDefinition, beanName));
 	}
 
 	/**
@@ -58,27 +57,21 @@ public class BeanComponentDefinition extends BeanDefinitionHolder implements Com
 	 * @param aliases alias names for the bean, or {@code null} if none
 	 */
 	public BeanComponentDefinition(BeanDefinition beanDefinition, String beanName, @Nullable String[] aliases) {
-		super(beanDefinition, beanName, aliases);
-		findInnerBeanDefinitionsAndBeanReferences(beanDefinition);
+		this(new BeanDefinitionHolder(beanDefinition, beanName, aliases));
 	}
 
 	/**
 	 * Create a new BeanComponentDefinition for the given bean.
-	 * @param holder the BeanDefinitionHolder encapsulating the
-	 * bean definition as well as the name of the bean
+	 * @param beanDefinitionHolder the BeanDefinitionHolder encapsulating
+	 * the bean definition as well as the name of the bean
 	 */
-	public BeanComponentDefinition(BeanDefinitionHolder holder) {
-		super(holder);
-		findInnerBeanDefinitionsAndBeanReferences(holder.getBeanDefinition());
-	}
-
+	public BeanComponentDefinition(BeanDefinitionHolder beanDefinitionHolder) {
+		super(beanDefinitionHolder);
 
-	private void findInnerBeanDefinitionsAndBeanReferences(BeanDefinition beanDefinition) {
 		List<BeanDefinition> innerBeans = new ArrayList<>();
 		List<BeanReference> references = new ArrayList<>();
-		PropertyValues propertyValues = beanDefinition.getPropertyValues();
-		for (int i = 0; i < propertyValues.getPropertyValues().length; i++) {
-			PropertyValue propertyValue = propertyValues.getPropertyValues()[i];
+		PropertyValues propertyValues = beanDefinitionHolder.getBeanDefinition().getPropertyValues();
+		for (PropertyValue propertyValue : propertyValues.getPropertyValues()) {
 			Object value = propertyValue.getValue();
 			if (value instanceof BeanDefinitionHolder) {
 				innerBeans.add(((BeanDefinitionHolder) value).getBeanDefinition());

spring-beans/src/main/java/org/springframework/beans/factory/support/BeanDefinitionBuilder.java

@@ -40,9 +40,7 @@ public class BeanDefinitionBuilder {
 	 * Create a new {@code BeanDefinitionBuilder} used to construct a {@link GenericBeanDefinition}.
 	 */
 	public static BeanDefinitionBuilder genericBeanDefinition() {
-		BeanDefinitionBuilder builder = new BeanDefinitionBuilder();
-		builder.beanDefinition = new GenericBeanDefinition();
-		return builder;
+		return new BeanDefinitionBuilder(new GenericBeanDefinition());
 	}
 
 	/**
@@ -50,8 +48,7 @@ public class BeanDefinitionBuilder {
 	 * @param beanClassName the class name for the bean that the definition is being created for
 	 */
 	public static BeanDefinitionBuilder genericBeanDefinition(String beanClassName) {
-		BeanDefinitionBuilder builder = new BeanDefinitionBuilder();
-		builder.beanDefinition = new GenericBeanDefinition();
+		BeanDefinitionBuilder builder = new BeanDefinitionBuilder(new GenericBeanDefinition());
 		builder.beanDefinition.setBeanClassName(beanClassName);
 		return builder;
 	}
@@ -61,8 +58,7 @@ public class BeanDefinitionBuilder {
 	 * @param beanClass the {@code Class} of the bean that the definition is being created for
 	 */
 	public static BeanDefinitionBuilder genericBeanDefinition(Class<?> beanClass) {
-		BeanDefinitionBuilder builder = new BeanDefinitionBuilder();
-		builder.beanDefinition = new GenericBeanDefinition();
+		BeanDefinitionBuilder builder = new BeanDefinitionBuilder(new GenericBeanDefinition());
 		builder.beanDefinition.setBeanClass(beanClass);
 		return builder;
 	}
@@ -76,8 +72,7 @@ public class BeanDefinitionBuilder {
 	public static <T> BeanDefinitionBuilder genericBeanDefinition(
 			@Nullable Class<T> beanClass, Supplier<T> instanceSupplier) {
 
-		BeanDefinitionBuilder builder = new BeanDefinitionBuilder();
-		builder.beanDefinition = new GenericBeanDefinition();
+		BeanDefinitionBuilder builder = new BeanDefinitionBuilder(new GenericBeanDefinition());
 		builder.beanDefinition.setBeanClass(beanClass);
 		builder.beanDefinition.setInstanceSupplier(instanceSupplier);
 		return builder;
@@ -97,8 +92,7 @@ public class BeanDefinitionBuilder {
 	 * @param factoryMethodName the name of the method to use to construct the bean instance
 	 */
 	public static BeanDefinitionBuilder rootBeanDefinition(String beanClassName, @Nullable String factoryMethodName) {
-		BeanDefinitionBuilder builder = new BeanDefinitionBuilder();
-		builder.beanDefinition = new RootBeanDefinition();
+		BeanDefinitionBuilder builder = new BeanDefinitionBuilder(new RootBeanDefinition());
 		builder.beanDefinition.setBeanClassName(beanClassName);
 		builder.beanDefinition.setFactoryMethodName(factoryMethodName);
 		return builder;
@@ -118,8 +112,7 @@ public class BeanDefinitionBuilder {
 	 * @param factoryMethodName the name of the method to use to construct the bean instance
 	 */
 	public static BeanDefinitionBuilder rootBeanDefinition(Class<?> beanClass, @Nullable String factoryMethodName) {
-		BeanDefinitionBuilder builder = new BeanDefinitionBuilder();
-		builder.beanDefinition = new RootBeanDefinition();
+		BeanDefinitionBuilder builder = new BeanDefinitionBuilder(new RootBeanDefinition());
 		builder.beanDefinition.setBeanClass(beanClass);
 		builder.beanDefinition.setFactoryMethodName(factoryMethodName);
 		return builder;
@@ -130,16 +123,14 @@ public class BeanDefinitionBuilder {
 	 * @param parentName the name of the parent bean
 	 */
 	public static BeanDefinitionBuilder childBeanDefinition(String parentName) {
-		BeanDefinitionBuilder builder = new BeanDefinitionBuilder();
-		builder.beanDefinition = new ChildBeanDefinition(parentName);
-		return builder;
+		return new BeanDefinitionBuilder(new ChildBeanDefinition(parentName));
 	}
 
 
 	/**
 	 * The {@code BeanDefinition} instance we are creating.
 	 */
-	private AbstractBeanDefinition beanDefinition;
+	private final AbstractBeanDefinition beanDefinition;
 
 	/**
 	 * Our current position with respect to constructor args.
@@ -150,7 +141,8 @@ public class BeanDefinitionBuilder {
 	/**
 	 * Enforce the use of factory methods.
 	 */
-	private BeanDefinitionBuilder() {
+	private BeanDefinitionBuilder(AbstractBeanDefinition beanDefinition) {
+		this.beanDefinition = beanDefinition;
 	}
 
 	/**

spring-beans/src/main/java/org/springframework/beans/factory/xml/DefaultBeanDefinitionDocumentReader.java

@@ -35,6 +35,7 @@ import org.springframework.beans.factory.support.BeanDefinitionReaderUtils;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.support.ResourcePatternUtils;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ResourceUtils;
 import org.springframework.util.StringUtils;
 
@@ -76,8 +77,10 @@ public class DefaultBeanDefinitionDocumentReader implements BeanDefinitionDocume
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private XmlReaderContext readerContext;
 
+	@Nullable
 	private BeanDefinitionParserDelegate delegate;
 
 
@@ -99,6 +102,7 @@ public class DefaultBeanDefinitionDocumentReader implements BeanDefinitionDocume
 	 * Return the descriptor for the XML resource that this parser works on.
 	 */
 	protected final XmlReaderContext getReaderContext() {
+		Assert.state(this.readerContext != null, "No XmlReaderContext available");
 		return this.readerContext;
 	}
 
@@ -148,7 +152,7 @@ public class DefaultBeanDefinitionDocumentReader implements BeanDefinitionDocume
 	}
 
 	protected BeanDefinitionParserDelegate createDelegate(
-			XmlReaderContext readerContext, Element root, BeanDefinitionParserDelegate parentDelegate) {
+			XmlReaderContext readerContext, Element root, @Nullable BeanDefinitionParserDelegate parentDelegate) {
 
 		BeanDefinitionParserDelegate delegate = new BeanDefinitionParserDelegate(readerContext);
 		delegate.initDefaults(root, parentDelegate);

spring-context-support/src/main/java/org/springframework/scheduling/commonj/ScheduledTimerListener.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.
@@ -18,6 +18,8 @@ package org.springframework.scheduling.commonj;
 
 import commonj.timers.TimerListener;
 
+import org.springframework.lang.Nullable;
+
 /**
  * JavaBean that describes a scheduled TimerListener, consisting of
  * the TimerListener itself (or a Runnable to create a TimerListener for)
@@ -40,6 +42,7 @@ import commonj.timers.TimerListener;
  */
 public class ScheduledTimerListener {
 
+	@Nullable
 	private TimerListener timerListener;
 
 	private long delay = 0;
@@ -140,13 +143,14 @@ public class ScheduledTimerListener {
 	/**
 	 * Set the TimerListener to schedule.
 	 */
-	public void setTimerListener(TimerListener timerListener) {
+	public void setTimerListener(@Nullable TimerListener timerListener) {
 		this.timerListener = timerListener;
 	}
 
 	/**
 	 * Return the TimerListener to schedule.
 	 */
+	@Nullable
 	public TimerListener getTimerListener() {
 		return this.timerListener;
 	}

spring-context-support/src/main/java/org/springframework/ui/freemarker/FreeMarkerConfigurationFactoryBean.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.
@@ -24,6 +24,7 @@ import freemarker.template.TemplateException;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.ResourceLoaderAware;
+import org.springframework.lang.Nullable;
 
 /**
  * Factory bean that creates a FreeMarker Configuration and provides it as
@@ -53,6 +54,7 @@ import org.springframework.context.ResourceLoaderAware;
 public class FreeMarkerConfigurationFactoryBean extends FreeMarkerConfigurationFactory
 		implements FactoryBean<Configuration>, InitializingBean, ResourceLoaderAware {
 
+	@Nullable
 	private Configuration configuration;
 
 

spring-context/src/main/java/org/springframework/cache/concurrent/ConcurrentMapCacheManager.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.
@@ -56,6 +56,7 @@ public class ConcurrentMapCacheManager implements CacheManager, BeanClassLoaderA
 
 	private boolean storeByValue = false;
 
+	@Nullable
 	private SerializationDelegate serialization;
 
 

spring-context/src/main/java/org/springframework/cache/interceptor/AbstractCacheInvoker.java

@@ -38,7 +38,7 @@ public abstract class AbstractCacheInvoker {
 	}
 
 	protected AbstractCacheInvoker(CacheErrorHandler errorHandler) {
-		setErrorHandler(errorHandler);
+		this.errorHandler = errorHandler;
 	}
 
 

spring-context/src/main/java/org/springframework/cache/interceptor/AbstractCacheResolver.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.
@@ -36,6 +36,7 @@ import org.springframework.util.Assert;
  */
 public abstract class AbstractCacheResolver implements CacheResolver, InitializingBean {
 
+	@Nullable
 	private CacheManager cacheManager;
 
 
@@ -55,15 +56,16 @@ public abstract class AbstractCacheResolver implements CacheResolver, Initializi
 	}
 
 	/**
-	 * Return the {@link CacheManager} that this instance use.
+	 * Return the {@link CacheManager} that this instance uses.
 	 */
 	public CacheManager getCacheManager() {
+		Assert.state(this.cacheManager != null, "No CacheManager set");
 		return this.cacheManager;
 	}
 
 	@Override
 	public void afterPropertiesSet()  {
-		Assert.notNull(this.cacheManager, "CacheManager must not be null");
+		Assert.notNull(this.cacheManager, "CacheManager is required");
 	}
 
 
@@ -76,7 +78,7 @@ public abstract class AbstractCacheResolver implements CacheResolver, Initializi
 		else {
 			Collection<Cache> result = new ArrayList<>();
 			for (String cacheName : cacheNames) {
-				Cache cache = this.cacheManager.getCache(cacheName);
+				Cache cache = getCacheManager().getCache(cacheName);
 				if (cache == null) {
 					throw new IllegalArgumentException("Cannot find cache named '" +
 							cacheName + "' for " + context.getOperation());

spring-context/src/main/java/org/springframework/cache/interceptor/BeanFactoryCacheOperationSourceAdvisor.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.
@@ -19,6 +19,7 @@ package org.springframework.cache.interceptor;
 import org.springframework.aop.ClassFilter;
 import org.springframework.aop.Pointcut;
 import org.springframework.aop.support.AbstractBeanFactoryPointcutAdvisor;
+import org.springframework.lang.Nullable;
 
 /**
  * Advisor driven by a {@link CacheOperationSource}, used to include a
@@ -30,6 +31,7 @@ import org.springframework.aop.support.AbstractBeanFactoryPointcutAdvisor;
 @SuppressWarnings("serial")
 public class BeanFactoryCacheOperationSourceAdvisor extends AbstractBeanFactoryPointcutAdvisor {
 
+	@Nullable
 	private CacheOperationSource cacheOperationSource;
 
 	private final CacheOperationSourcePointcut pointcut = new CacheOperationSourcePointcut() {

spring-context/src/main/java/org/springframework/cache/interceptor/CachePutOperation.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.
@@ -16,6 +16,8 @@
 
 package org.springframework.cache.interceptor;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Class describing a cache 'put' operation.
  *
@@ -26,6 +28,7 @@ package org.springframework.cache.interceptor;
  */
 public class CachePutOperation extends CacheOperation {
 
+	@Nullable
 	private final String unless;
 
 
@@ -38,6 +41,7 @@ public class CachePutOperation extends CacheOperation {
 	}
 
 
+	@Nullable
 	public String getUnless() {
 		return this.unless;
 	}
@@ -48,6 +52,7 @@ public class CachePutOperation extends CacheOperation {
 	 */
 	public static class Builder extends CacheOperation.Builder {
 
+		@Nullable
 		private String unless;
 
 		public void setUnless(String unless) {

spring-context/src/main/java/org/springframework/cache/interceptor/CacheableOperation.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.
@@ -16,6 +16,8 @@
 
 package org.springframework.cache.interceptor;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Class describing a cache 'cacheable' operation.
  *
@@ -26,6 +28,7 @@ package org.springframework.cache.interceptor;
  */
 public class CacheableOperation extends CacheOperation {
 
+	@Nullable
 	private final String unless;
 
 	private final boolean sync;
@@ -41,6 +44,7 @@ public class CacheableOperation extends CacheOperation {
 	}
 
 
+	@Nullable
 	public String getUnless() {
 		return this.unless;
 	}
@@ -55,6 +59,7 @@ public class CacheableOperation extends CacheOperation {
 	 */
 	public static class Builder extends CacheOperation.Builder {
 
+		@Nullable
 		private String unless;
 
 		private boolean sync;

spring-context/src/main/java/org/springframework/cache/interceptor/NamedCacheResolver.java

@@ -16,12 +16,12 @@
 
 package org.springframework.cache.interceptor;
 
-
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 
 import org.springframework.cache.CacheManager;
+import org.springframework.lang.Nullable;
 
 /**
  * A {@link CacheResolver} that forces the resolution to a configurable
@@ -32,6 +32,7 @@ import org.springframework.cache.CacheManager;
  */
 public class NamedCacheResolver extends AbstractCacheResolver {
 
+	@Nullable
 	private Collection<String> cacheNames;
 
 

spring-context/src/main/java/org/springframework/cache/interceptor/SimpleCacheErrorHandler.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.
@@ -17,6 +17,7 @@
 package org.springframework.cache.interceptor;
 
 import org.springframework.cache.Cache;
+import org.springframework.lang.Nullable;
 
 /**
  * A simple {@link CacheErrorHandler} that does not handle the
@@ -33,7 +34,7 @@ public class SimpleCacheErrorHandler implements CacheErrorHandler {
 	}
 
 	@Override
-	public void handleCachePutError(RuntimeException exception, Cache cache, Object key, Object value) {
+	public void handleCachePutError(RuntimeException exception, Cache cache, Object key, @Nullable Object value) {
 		throw exception;
 	}
 

spring-context/src/main/java/org/springframework/cache/support/SimpleCacheManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 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.cache.support;
 
 import java.util.Collection;
+import java.util.Collections;
 
 import org.springframework.cache.Cache;
 
@@ -29,7 +30,7 @@ import org.springframework.cache.Cache;
  */
 public class SimpleCacheManager extends AbstractCacheManager {
 
-	private Collection<? extends Cache> caches;
+	private Collection<? extends Cache> caches = Collections.emptySet();
 
 
 	/**

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClass.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.
@@ -53,6 +53,7 @@ final class ConfigurationClass {
 
 	private final Resource resource;
 
+	@Nullable
 	private String beanName;
 
 	private final Set<ConfigurationClass> importedBy = new LinkedHashSet<>(1);
@@ -75,7 +76,7 @@ final class ConfigurationClass {
 	 * @see ConfigurationClass#ConfigurationClass(Class, ConfigurationClass)
 	 */
 	public ConfigurationClass(MetadataReader metadataReader, String beanName) {
-		Assert.hasText(beanName, "Bean name must not be null");
+		Assert.notNull(beanName, "Bean name must not be null");
 		this.metadata = metadataReader.getAnnotationMetadata();
 		this.resource = metadataReader.getResource();
 		this.beanName = beanName;
@@ -102,7 +103,7 @@ final class ConfigurationClass {
 	 * @see ConfigurationClass#ConfigurationClass(Class, ConfigurationClass)
 	 */
 	public ConfigurationClass(Class<?> clazz, String beanName) {
-		Assert.hasText(beanName, "Bean name must not be null");
+		Assert.notNull(beanName, "Bean name must not be null");
 		this.metadata = new StandardAnnotationMetadata(clazz, true);
 		this.resource = new DescriptiveResource(clazz.getName());
 		this.beanName = beanName;
@@ -113,7 +114,7 @@ final class ConfigurationClass {
 	 * using the {@link Import} annotation or automatically processed as a nested
 	 * configuration class (if imported is {@code true}).
 	 * @param clazz the underlying {@link Class} to represent
-	 * @param importedBy the configuration class importing this one or {@code null}
+	 * @param importedBy the configuration class importing this one (or {@code null})
 	 * @since 3.1.1
 	 */
 	public ConfigurationClass(Class<?> clazz, @Nullable ConfigurationClass importedBy) {
@@ -129,7 +130,7 @@ final class ConfigurationClass {
 	 * @see ConfigurationClass#ConfigurationClass(Class, ConfigurationClass)
 	 */
 	public ConfigurationClass(AnnotationMetadata metadata, String beanName) {
-		Assert.hasText(beanName, "Bean name must not be null");
+		Assert.notNull(beanName, "Bean name must not be null");
 		this.metadata = metadata;
 		this.resource = new DescriptiveResource(metadata.getClassName());
 		this.beanName = beanName;
@@ -152,6 +153,7 @@ final class ConfigurationClass {
 		this.beanName = beanName;
 	}
 
+	@Nullable
 	public String getBeanName() {
 		return this.beanName;
 	}

spring-context/src/main/java/org/springframework/context/event/EventListenerMethodProcessor.java

@@ -31,7 +31,6 @@ import org.springframework.aop.framework.autoproxy.AutoProxyUtils;
 import org.springframework.aop.scope.ScopedObject;
 import org.springframework.aop.scope.ScopedProxyUtils;
 import org.springframework.aop.support.AopUtils;
-import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.beans.factory.SmartInitializingSingleton;
 import org.springframework.context.ApplicationContext;
@@ -41,6 +40,7 @@ import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.MethodIntrospector;
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 
@@ -56,6 +56,7 @@ public class EventListenerMethodProcessor implements SmartInitializingSingleton,
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private ConfigurableApplicationContext applicationContext;
 
 	private final EventExpressionEvaluator evaluator = new EventExpressionEvaluator();
@@ -64,21 +65,28 @@ public class EventListenerMethodProcessor implements SmartInitializingSingleton,
 
 
 	@Override
-	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
+	public void setApplicationContext(ApplicationContext applicationContext) {
 		Assert.isTrue(applicationContext instanceof ConfigurableApplicationContext,
 				"ApplicationContext does not implement ConfigurableApplicationContext");
 		this.applicationContext = (ConfigurableApplicationContext) applicationContext;
 	}
 
+	private ConfigurableApplicationContext getApplicationContext() {
+		Assert.state(this.applicationContext != null, "No ApplicationContext set");
+		return this.applicationContext;
+	}
+
+
 	@Override
 	public void afterSingletonsInstantiated() {
 		List<EventListenerFactory> factories = getEventListenerFactories();
-		String[] beanNames = this.applicationContext.getBeanNamesForType(Object.class);
+		ConfigurableApplicationContext context = getApplicationContext();
+		String[] beanNames = context.getBeanNamesForType(Object.class);
 		for (String beanName : beanNames) {
 			if (!ScopedProxyUtils.isScopedTarget(beanName)) {
 				Class<?> type = null;
 				try {
-					type = AutoProxyUtils.determineTargetClass(this.applicationContext.getBeanFactory(), beanName);
+					type = AutoProxyUtils.determineTargetClass(context.getBeanFactory(), beanName);
 				}
 				catch (Throwable ex) {
 					// An unresolvable bean type, probably from a lazy bean - let's ignore it.
@@ -90,8 +98,7 @@ public class EventListenerMethodProcessor implements SmartInitializingSingleton,
 					if (ScopedObject.class.isAssignableFrom(type)) {
 						try {
 							Class<?> targetClass = AutoProxyUtils.determineTargetClass(
-									this.applicationContext.getBeanFactory(),
-									ScopedProxyUtils.getTargetBeanName(beanName));
+									context.getBeanFactory(), ScopedProxyUtils.getTargetBeanName(beanName));
 							if (targetClass != null) {
 								type = targetClass;
 							}
@@ -121,7 +128,7 @@ public class EventListenerMethodProcessor implements SmartInitializingSingleton,
 	 * {@link EventListener} annotated methods.
 	 */
 	protected List<EventListenerFactory> getEventListenerFactories() {
-		Map<String, EventListenerFactory> beans = this.applicationContext.getBeansOfType(EventListenerFactory.class);
+		Map<String, EventListenerFactory> beans = getApplicationContext().getBeansOfType(EventListenerFactory.class);
 		List<EventListenerFactory> allFactories = new ArrayList<>(beans.values());
 		AnnotationAwareOrderComparator.sort(allFactories);
 		return allFactories;
@@ -152,18 +159,17 @@ public class EventListenerMethodProcessor implements SmartInitializingSingleton,
 			}
 			else {
 				// Non-empty set of methods
+				ConfigurableApplicationContext context = getApplicationContext();
 				for (Method method : annotatedMethods.keySet()) {
 					for (EventListenerFactory factory : factories) {
 						if (factory.supportsMethod(method)) {
-							Method methodToUse = AopUtils.selectInvocableMethod(
-									method, this.applicationContext.getType(beanName));
+							Method methodToUse = AopUtils.selectInvocableMethod(method, context.getType(beanName));
 							ApplicationListener<?> applicationListener =
 									factory.createApplicationListener(beanName, targetType, methodToUse);
 							if (applicationListener instanceof ApplicationListenerMethodAdapter) {
-								((ApplicationListenerMethodAdapter) applicationListener)
-										.init(this.applicationContext, this.evaluator);
+								((ApplicationListenerMethodAdapter) applicationListener).init(context, this.evaluator);
 							}
-							this.applicationContext.addApplicationListener(applicationListener);
+							context.addApplicationListener(applicationListener);
 							break;
 						}
 					}

spring-context/src/main/java/org/springframework/context/support/ApplicationListenerDetector.java

@@ -27,7 +27,6 @@ import org.springframework.beans.factory.support.MergedBeanDefinitionPostProcess
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.event.ApplicationEventMulticaster;
-import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -47,7 +46,6 @@ class ApplicationListenerDetector implements DestructionAwareBeanPostProcessor,
 
 	private static final Log logger = LogFactory.getLog(ApplicationListenerDetector.class);
 
-	@Nullable
 	private transient final AbstractApplicationContext applicationContext;
 
 	private transient final Map<String, Boolean> singletonNames = new ConcurrentHashMap<>(256);
@@ -60,9 +58,7 @@ class ApplicationListenerDetector implements DestructionAwareBeanPostProcessor,
 
 	@Override
 	public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
-		if (this.applicationContext != null) {
-			this.singletonNames.put(beanName, beanDefinition.isSingleton());
-		}
+		this.singletonNames.put(beanName, beanDefinition.isSingleton());
 	}
 
 	@Override
@@ -72,7 +68,7 @@ class ApplicationListenerDetector implements DestructionAwareBeanPostProcessor,
 
 	@Override
 	public Object postProcessAfterInitialization(Object bean, String beanName) {
-		if (this.applicationContext != null && bean instanceof ApplicationListener) {
+		if (bean instanceof ApplicationListener) {
 			// potentially not detected as a listener by getBeanNamesForType retrieval
 			Boolean flag = this.singletonNames.get(beanName);
 			if (Boolean.TRUE.equals(flag)) {
@@ -95,7 +91,7 @@ class ApplicationListenerDetector implements DestructionAwareBeanPostProcessor,
 
 	@Override
 	public void postProcessBeforeDestruction(Object bean, String beanName) {
-		if (this.applicationContext != null && bean instanceof ApplicationListener) {
+		if (bean instanceof ApplicationListener) {
 			ApplicationEventMulticaster multicaster = this.applicationContext.getApplicationEventMulticaster();
 			multicaster.removeApplicationListener((ApplicationListener<?>) bean);
 			multicaster.removeApplicationListenerBean(beanName);

spring-context/src/main/java/org/springframework/context/support/ClassPathXmlApplicationContext.java

@@ -51,6 +51,7 @@ import org.springframework.util.Assert;
  */
 public class ClassPathXmlApplicationContext extends AbstractXmlApplicationContext {
 
+	@Nullable
 	private Resource[] configResources;
 
 
@@ -203,6 +204,7 @@ public class ClassPathXmlApplicationContext extends AbstractXmlApplicationContex
 
 
 	@Override
+	@Nullable
 	protected Resource[] getConfigResources() {
 		return this.configResources;
 	}

spring-context/src/main/java/org/springframework/context/support/ConversionServiceFactoryBean.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.
@@ -24,6 +24,7 @@ import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.support.ConversionServiceFactory;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.core.convert.support.GenericConversionService;
+import org.springframework.lang.Nullable;
 
 /**
  * A factory providing convenient access to a ConversionService configured with
@@ -49,8 +50,10 @@ import org.springframework.core.convert.support.GenericConversionService;
  */
 public class ConversionServiceFactoryBean implements FactoryBean<ConversionService>, InitializingBean {
 
+	@Nullable
 	private Set<?> converters;
 
+	@Nullable
 	private GenericConversionService conversionService;
 
 

spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java

@@ -39,6 +39,8 @@ import org.springframework.context.Lifecycle;
 import org.springframework.context.LifecycleProcessor;
 import org.springframework.context.Phased;
 import org.springframework.context.SmartLifecycle;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Default implementation of the {@link LifecycleProcessor} strategy.
@@ -55,6 +57,7 @@ public class DefaultLifecycleProcessor implements LifecycleProcessor, BeanFactor
 
 	private volatile boolean running;
 
+	@Nullable
 	private volatile ConfigurableListableBeanFactory beanFactory;
 
 
@@ -76,6 +79,12 @@ public class DefaultLifecycleProcessor implements LifecycleProcessor, BeanFactor
 		this.beanFactory = (ConfigurableListableBeanFactory) beanFactory;
 	}
 
+	private ConfigurableListableBeanFactory getBeanFactory() {
+		ConfigurableListableBeanFactory beanFactory = this.beanFactory;
+		Assert.state(beanFactory != null, "No BeanFactory available");
+		return beanFactory;
+	}
+
 
 	// Lifecycle implementation
 
@@ -161,7 +170,7 @@ public class DefaultLifecycleProcessor implements LifecycleProcessor, BeanFactor
 	private void doStart(Map<String, ? extends Lifecycle> lifecycleBeans, String beanName, boolean autoStartupOnly) {
 		Lifecycle bean = lifecycleBeans.remove(beanName);
 		if (bean != null && !this.equals(bean)) {
-			String[] dependenciesForBean = this.beanFactory.getDependenciesForBean(beanName);
+			String[] dependenciesForBean = getBeanFactory().getDependenciesForBean(beanName);
 			for (String dependency : dependenciesForBean) {
 				doStart(lifecycleBeans, dependency, autoStartupOnly);
 			}
@@ -215,7 +224,7 @@ public class DefaultLifecycleProcessor implements LifecycleProcessor, BeanFactor
 
 		Lifecycle bean = lifecycleBeans.remove(beanName);
 		if (bean != null) {
-			String[] dependentBeans = this.beanFactory.getDependentBeans(beanName);
+			String[] dependentBeans = getBeanFactory().getDependentBeans(beanName);
 			for (String dependentBean : dependentBeans) {
 				doStop(lifecycleBeans, dependentBean, latch, countDownBeanNames);
 			}
@@ -266,16 +275,17 @@ public class DefaultLifecycleProcessor implements LifecycleProcessor, BeanFactor
 	 * @return the Map of applicable beans, with bean names as keys and bean instances as values
 	 */
 	protected Map<String, Lifecycle> getLifecycleBeans() {
+		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
 		Map<String, Lifecycle> beans = new LinkedHashMap<>();
-		String[] beanNames = this.beanFactory.getBeanNamesForType(Lifecycle.class, false, false);
+		String[] beanNames = getBeanFactory().getBeanNamesForType(Lifecycle.class, false, false);
 		for (String beanName : beanNames) {
 			String beanNameToRegister = BeanFactoryUtils.transformedBeanName(beanName);
-			boolean isFactoryBean = this.beanFactory.isFactoryBean(beanNameToRegister);
+			boolean isFactoryBean = getBeanFactory().isFactoryBean(beanNameToRegister);
 			String beanNameToCheck = (isFactoryBean ? BeanFactory.FACTORY_BEAN_PREFIX + beanName : beanName);
-			if ((this.beanFactory.containsSingleton(beanNameToRegister) &&
+			if ((getBeanFactory().containsSingleton(beanNameToRegister) &&
 					(!isFactoryBean || matchesBeanType(Lifecycle.class, beanNameToCheck))) ||
 					matchesBeanType(SmartLifecycle.class, beanNameToCheck)) {
-				Lifecycle bean = this.beanFactory.getBean(beanNameToCheck, Lifecycle.class);
+				Lifecycle bean = getBeanFactory().getBean(beanNameToCheck, Lifecycle.class);
 				if (bean != this) {
 					beans.put(beanNameToRegister, bean);
 				}
@@ -285,7 +295,7 @@ public class DefaultLifecycleProcessor implements LifecycleProcessor, BeanFactor
 	}
 
 	private boolean matchesBeanType(Class<?> targetType, String beanName) {
-		Class<?> beanType = this.beanFactory.getType(beanName);
+		Class<?> beanType = getBeanFactory().getType(beanName);
 		return (beanType != null && targetType.isAssignableFrom(beanType));
 	}
 

spring-context/src/main/java/org/springframework/context/weaving/AspectJWeavingEnabler.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.
@@ -47,8 +47,10 @@ public class AspectJWeavingEnabler
 	public static final String ASPECTJ_AOP_XML_RESOURCE = "META-INF/aop.xml";
 
 
+	@Nullable
 	private ClassLoader beanClassLoader;
 
+	@Nullable
 	private LoadTimeWeaver loadTimeWeaver;
 
 

spring-context/src/main/java/org/springframework/format/datetime/joda/DateTimeFormatterFactoryBean.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.
@@ -20,6 +20,7 @@ import org.joda.time.format.DateTimeFormatter;
 
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link FactoryBean} that creates a Joda-Time {@link DateTimeFormatter}.
@@ -36,6 +37,7 @@ import org.springframework.beans.factory.InitializingBean;
 public class DateTimeFormatterFactoryBean extends DateTimeFormatterFactory
 		implements FactoryBean<DateTimeFormatter>, InitializingBean {
 
+	@Nullable
 	private DateTimeFormatter dateTimeFormatter;
 
 

spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactoryBean.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.
@@ -20,6 +20,7 @@ import java.time.format.DateTimeFormatter;
 
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link FactoryBean} that creates a JSR-310 {@link java.time.format.DateTimeFormatter}.
@@ -36,6 +37,7 @@ import org.springframework.beans.factory.InitializingBean;
 public class DateTimeFormatterFactoryBean extends DateTimeFormatterFactory
 		implements FactoryBean<DateTimeFormatter>, InitializingBean {
 
+	@Nullable
 	private DateTimeFormatter dateTimeFormatter;
 
 

spring-context/src/main/java/org/springframework/jmx/export/assembler/MetadataMBeanInfoAssembler.java

@@ -432,7 +432,8 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	 * @param setter the Object value associated with the set method
 	 * @return the appropriate Object to use as the value for the descriptor
 	 */
-	private Object resolveObjectDescriptor(@Nullable Object getter, Object setter) {
+	@Nullable
+	private Object resolveObjectDescriptor(@Nullable Object getter, @Nullable Object setter) {
 		return (getter != null ? getter : setter);
 	}
 
@@ -446,7 +447,8 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	 * @param setter the String value associated with the set method
 	 * @return the appropriate String to use as the value for the descriptor
 	 */
-	private String resolveStringDescriptor(String getter, String setter) {
+	@Nullable
+	private String resolveStringDescriptor(@Nullable String getter, @Nullable String setter) {
 		return (StringUtils.hasLength(getter) ? getter : setter);
 	}
 

spring-context/src/main/java/org/springframework/jmx/export/metadata/ManagedAttribute.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2007 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.jmx.export.metadata;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Metadata that indicates to expose a given bean property as JMX attribute.
  * Only valid when used on a JavaBean getter or setter.
@@ -30,8 +32,10 @@ public class ManagedAttribute extends AbstractJmxAttribute {
 	public static final ManagedAttribute EMPTY = new ManagedAttribute();
 
 
+	@Nullable
 	private Object defaultValue;
 
+	@Nullable
 	private String persistPolicy;
 
 	private int persistPeriod = -1;
@@ -40,21 +44,23 @@ public class ManagedAttribute extends AbstractJmxAttribute {
 	/**
 	 * Set the default value of this attribute.
 	 */
-	public void setDefaultValue(Object defaultValue) {
+	public void setDefaultValue(@Nullable Object defaultValue) {
 		this.defaultValue = defaultValue;
 	}
 
 	/**
 	 * Return the default value of this attribute.
 	 */
+	@Nullable
 	public Object getDefaultValue() {
 		return this.defaultValue;
 	}
 
-	public void setPersistPolicy(String persistPolicy) {
+	public void setPersistPolicy(@Nullable String persistPolicy) {
 		this.persistPolicy = persistPolicy;
 	}
 
+	@Nullable
 	public String getPersistPolicy() {
 		return this.persistPolicy;
 	}

spring-context/src/main/java/org/springframework/jmx/export/metadata/ManagedMetric.java

@@ -17,6 +17,7 @@
 package org.springframework.jmx.export.metadata;
 
 import org.springframework.jmx.support.MetricType;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -30,29 +31,34 @@ import org.springframework.util.Assert;
  */
 public class ManagedMetric extends AbstractJmxAttribute {
 
+	@Nullable
 	private String category;
 
+	@Nullable
 	private String displayName;
 
 	private MetricType metricType = MetricType.GAUGE;
 
 	private int persistPeriod = -1;
 
+	@Nullable
 	private String persistPolicy;
 
+	@Nullable
 	private String unit;
 
 
 	/**
 	 * The category of this metric (ex. throughput, performance, utilization).
 	 */
-	public void setCategory(String category) {
+	public void setCategory(@Nullable String category) {
 		this.category = category;
 	}
 
 	/**
 	 * The category of this metric (ex. throughput, performance, utilization).
 	 */
+	@Nullable
 	public String getCategory() {
 		return this.category;
 	}
@@ -60,13 +66,14 @@ public class ManagedMetric extends AbstractJmxAttribute {
 	/**
 	 * A display name for this metric.
 	 */
-	public void setDisplayName(String displayName) {
+	public void setDisplayName(@Nullable String displayName) {
 		this.displayName = displayName;
 	}
 
 	/**
 	 * A display name for this metric.
 	 */
+	@Nullable
 	public String getDisplayName() {
 		return this.displayName;
 	}
@@ -103,13 +110,14 @@ public class ManagedMetric extends AbstractJmxAttribute {
 	/**
 	 * The persist policy for this metric.
 	 */
-	public void setPersistPolicy(String persistPolicy) {
+	public void setPersistPolicy(@Nullable String persistPolicy) {
 		this.persistPolicy = persistPolicy;
 	}
 
 	/**
 	 * The persist policy for this metric.
 	 */
+	@Nullable
 	public String getPersistPolicy() {
 		return this.persistPolicy;
 	}
@@ -117,13 +125,14 @@ public class ManagedMetric extends AbstractJmxAttribute {
 	/**
 	 * The expected unit of measurement values.
 	 */
-	public void setUnit(String unit) {
+	public void setUnit(@Nullable String unit) {
 		this.unit = unit;
 	}
 
 	/**
 	 * The expected unit of measurement values.
 	 */
+	@Nullable
 	public String getUnit() {
 		return this.unit;
 	}

spring-context/src/main/java/org/springframework/jmx/export/metadata/ManagedResource.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.
@@ -16,6 +16,8 @@
 
 package org.springframework.jmx.export.metadata;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Metadata indicating that instances of an annotated class
  * are to be registered with a JMX server.
@@ -29,31 +31,37 @@ package org.springframework.jmx.export.metadata;
  */
 public class ManagedResource extends AbstractJmxAttribute {
 
+	@Nullable
 	private String objectName;
 
 	private boolean log = false;
 
+	@Nullable
 	private String logFile;
 
+	@Nullable
 	private String persistPolicy;
 
 	private int persistPeriod = -1;
 
+	@Nullable
 	private String persistName;
 
+	@Nullable
 	private String persistLocation;
 
 
 	/**
 	 * Set the JMX ObjectName of this managed resource.
 	 */
-	public void setObjectName(String objectName) {
+	public void setObjectName(@Nullable String objectName) {
 		this.objectName = objectName;
 	}
 
 	/**
 	 * Return the JMX ObjectName of this managed resource.
 	 */
+	@Nullable
 	public String getObjectName() {
 		return this.objectName;
 	}
@@ -66,18 +74,20 @@ public class ManagedResource extends AbstractJmxAttribute {
 		return this.log;
 	}
 
-	public void setLogFile(String logFile) {
+	public void setLogFile(@Nullable String logFile) {
 		this.logFile = logFile;
 	}
 
+	@Nullable
 	public String getLogFile() {
 		return this.logFile;
 	}
 
-	public void setPersistPolicy(String persistPolicy) {
+	public void setPersistPolicy(@Nullable String persistPolicy) {
 		this.persistPolicy = persistPolicy;
 	}
 
+	@Nullable
 	public String getPersistPolicy() {
 		return this.persistPolicy;
 	}
@@ -90,18 +100,20 @@ public class ManagedResource extends AbstractJmxAttribute {
 		return this.persistPeriod;
 	}
 
-	public void setPersistName(String persistName) {
+	public void setPersistName(@Nullable String persistName) {
 		this.persistName = persistName;
 	}
 
+	@Nullable
 	public String getPersistName() {
 		return this.persistName;
 	}
 
-	public void setPersistLocation(String persistLocation) {
+	public void setPersistLocation(@Nullable String persistLocation) {
 		this.persistLocation = persistLocation;
 	}
 
+	@Nullable
 	public String getPersistLocation() {
 		return this.persistLocation;
 	}

spring-context/src/main/java/org/springframework/jndi/TypeMismatchNamingException.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.
@@ -29,9 +29,9 @@ import javax.naming.NamingException;
 @SuppressWarnings("serial")
 public class TypeMismatchNamingException extends NamingException {
 
-	private Class<?> requiredType;
+	private final Class<?> requiredType;
 
-	private Class<?> actualType;
+	private final Class<?> actualType;
 
 
 	/**
@@ -48,14 +48,6 @@ public class TypeMismatchNamingException extends NamingException {
 		this.actualType = actualType;
 	}
 
-	/**
-	 * Construct a new TypeMismatchNamingException.
-	 * @param explanation the explanation text
-	 */
-	public TypeMismatchNamingException(String explanation) {
-		super(explanation);
-	}
-
 
 	/**
 	 * Return the required type for the lookup, if available.

spring-context/src/main/java/org/springframework/remoting/support/RemoteInvocationResult.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.
@@ -20,6 +20,7 @@ import java.io.Serializable;
 import java.lang.reflect.InvocationTargetException;
 
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Encapsulates a remote invocation result, holding a result value or an exception.
@@ -53,7 +54,7 @@ public class RemoteInvocationResult implements Serializable {
 	 * @param value the result value returned by a successful invocation
 	 * of the target method
 	 */
-	public RemoteInvocationResult(Object value) {
+	public RemoteInvocationResult(@Nullable Object value) {
 		this.value = value;
 	}
 
@@ -62,7 +63,7 @@ public class RemoteInvocationResult implements Serializable {
 	 * @param exception the exception thrown by an unsuccessful invocation
 	 * of the target method
 	 */
-	public RemoteInvocationResult(Throwable exception) {
+	public RemoteInvocationResult(@Nullable Throwable exception) {
 		this.exception = exception;
 	}
 

spring-context/src/main/java/org/springframework/scheduling/concurrent/ConcurrentTaskExecutor.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.
@@ -88,17 +88,19 @@ public class ConcurrentTaskExecutor implements AsyncListenableTaskExecutor, Sche
 	 * @see java.util.concurrent.Executors#newSingleThreadExecutor()
 	 */
 	public ConcurrentTaskExecutor() {
-		setConcurrentExecutor(null);
+		this.concurrentExecutor = Executors.newSingleThreadExecutor();
+		this.adaptedExecutor = new TaskExecutorAdapter(this.concurrentExecutor);
 	}
 
 	/**
 	 * Create a new ConcurrentTaskExecutor, using the given {@link java.util.concurrent.Executor}.
 	 * <p>Autodetects a JSR-236 {@link javax.enterprise.concurrent.ManagedExecutorService}
 	 * in order to expose {@link javax.enterprise.concurrent.ManagedTask} adapters for it.
-	 * @param concurrentExecutor the {@link java.util.concurrent.Executor} to delegate to
+	 * @param executor the {@link java.util.concurrent.Executor} to delegate to
 	 */
-	public ConcurrentTaskExecutor(Executor concurrentExecutor) {
-		setConcurrentExecutor(concurrentExecutor);
+	public ConcurrentTaskExecutor(@Nullable Executor executor) {
+		this.concurrentExecutor = (executor != null ? executor : Executors.newSingleThreadExecutor());
+		this.adaptedExecutor = getAdaptedExecutor(this.concurrentExecutor);
 	}
 
 
@@ -107,20 +109,9 @@ public class ConcurrentTaskExecutor implements AsyncListenableTaskExecutor, Sche
 	 * <p>Autodetects a JSR-236 {@link javax.enterprise.concurrent.ManagedExecutorService}
 	 * in order to expose {@link javax.enterprise.concurrent.ManagedTask} adapters for it.
 	 */
-	public final void setConcurrentExecutor(@Nullable Executor concurrentExecutor) {
-		if (concurrentExecutor != null) {
-			this.concurrentExecutor = concurrentExecutor;
-			if (managedExecutorServiceClass != null && managedExecutorServiceClass.isInstance(concurrentExecutor)) {
-				this.adaptedExecutor = new ManagedTaskExecutorAdapter(concurrentExecutor);
-			}
-			else {
-				this.adaptedExecutor = new TaskExecutorAdapter(concurrentExecutor);
-			}
-		}
-		else {
-			this.concurrentExecutor = Executors.newSingleThreadExecutor();
-			this.adaptedExecutor = new TaskExecutorAdapter(this.concurrentExecutor);
-		}
+	public final void setConcurrentExecutor(@Nullable Executor executor) {
+		this.concurrentExecutor = (executor != null ? executor : Executors.newSingleThreadExecutor());
+		this.adaptedExecutor = getAdaptedExecutor(this.concurrentExecutor);
 	}
 
 	/**
@@ -184,6 +175,14 @@ public class ConcurrentTaskExecutor implements AsyncListenableTaskExecutor, Sche
 	}
 
 
+	private static TaskExecutorAdapter getAdaptedExecutor(Executor concurrentExecutor) {
+		if (managedExecutorServiceClass != null && managedExecutorServiceClass.isInstance(concurrentExecutor)) {
+			return new ManagedTaskExecutorAdapter(concurrentExecutor);
+		}
+		return new TaskExecutorAdapter(concurrentExecutor);
+	}
+
+
 	/**
 	 * TaskExecutorAdapter subclass that wraps all provided Runnables and Callables
 	 * with a JSR-236 ManagedTask, exposing a long-running hint based on

spring-context/src/main/java/org/springframework/scheduling/concurrent/ForkJoinPoolFactoryBean.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.
@@ -22,6 +22,7 @@ import java.util.concurrent.TimeUnit;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
 
 /**
  * A Spring {@link FactoryBean} that builds and exposes a preconfigured {@link ForkJoinPool}.
@@ -43,12 +44,14 @@ public class ForkJoinPoolFactoryBean implements FactoryBean<ForkJoinPool>, Initi
 
 	private ForkJoinPool.ForkJoinWorkerThreadFactory threadFactory = ForkJoinPool.defaultForkJoinWorkerThreadFactory;
 
+	@Nullable
 	private Thread.UncaughtExceptionHandler uncaughtExceptionHandler;
 
 	private boolean asyncMode = false;
 
 	private int awaitTerminationSeconds = 0;
 
+	@Nullable
 	private ForkJoinPool forkJoinPool;
 
 
@@ -148,16 +151,18 @@ public class ForkJoinPoolFactoryBean implements FactoryBean<ForkJoinPool>, Initi
 
 	@Override
 	public void destroy() {
-		// Ignored for the common pool.
-		this.forkJoinPool.shutdown();
-
-		// Wait for all tasks to terminate - works for the common pool as well.
-		if (this.awaitTerminationSeconds > 0) {
-			try {
-				this.forkJoinPool.awaitTermination(this.awaitTerminationSeconds, TimeUnit.SECONDS);
-			}
-			catch (InterruptedException ex) {
-				Thread.currentThread().interrupt();
+		if (this.forkJoinPool != null) {
+			// Ignored for the common pool.
+			this.forkJoinPool.shutdown();
+
+			// Wait for all tasks to terminate - works for the common pool as well.
+			if (this.awaitTerminationSeconds > 0) {
+				try {
+					this.forkJoinPool.awaitTermination(this.awaitTerminationSeconds, TimeUnit.SECONDS);
+				}
+				catch (InterruptedException ex) {
+					Thread.currentThread().interrupt();
+				}
 			}
 		}
 	}

spring-context/src/main/java/org/springframework/scheduling/concurrent/ScheduledExecutorTask.java

@@ -19,6 +19,7 @@ package org.springframework.scheduling.concurrent;
 import java.util.concurrent.TimeUnit;
 
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * JavaBean that describes a scheduled executor task, consisting of the
@@ -40,6 +41,7 @@ import org.springframework.lang.Nullable;
  */
 public class ScheduledExecutorTask {
 
+	@Nullable
 	private Runnable runnable;
 
 	private long delay = 0;
@@ -107,6 +109,7 @@ public class ScheduledExecutorTask {
 	 * Return the Runnable to schedule as executor task.
 	 */
 	public Runnable getRunnable() {
+		Assert.state(this.runnable != null, "No Runnable set");
 		return this.runnable;
 	}
 

spring-context/src/main/java/org/springframework/scheduling/support/SimpleTriggerContext.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.
@@ -18,6 +18,7 @@ package org.springframework.scheduling.support;
 
 import java.util.Date;
 
+import org.springframework.lang.Nullable;
 import org.springframework.scheduling.TriggerContext;
 
 /**
@@ -28,10 +29,13 @@ import org.springframework.scheduling.TriggerContext;
  */
 public class SimpleTriggerContext implements TriggerContext {
 
+	@Nullable
 	private volatile Date lastScheduledExecutionTime;
 
+	@Nullable
 	private volatile Date lastActualExecutionTime;
 
+	@Nullable
 	private volatile Date lastCompletionTime;
 
 

spring-context/src/main/java/org/springframework/scripting/ScriptCompilationException.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.
@@ -28,6 +28,7 @@ import org.springframework.lang.Nullable;
 @SuppressWarnings("serial")
 public class ScriptCompilationException extends NestedRuntimeException {
 
+	@Nullable
 	private ScriptSource scriptSource;
 
 

spring-context/src/main/java/org/springframework/scripting/bsh/BshScriptEvaluator.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.
@@ -38,6 +38,7 @@ import org.springframework.scripting.ScriptSource;
  */
 public class BshScriptEvaluator implements ScriptEvaluator, BeanClassLoaderAware {
 
+	@Nullable
 	private ClassLoader classLoader;
 
 

spring-context/src/main/java/org/springframework/ui/ExtendedModelMap.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.
@@ -49,19 +49,19 @@ public class ExtendedModelMap extends ModelMap implements Model {
 	}
 
 	@Override
-	public ExtendedModelMap addAllAttributes(Collection<?> attributeValues) {
+	public ExtendedModelMap addAllAttributes(@Nullable Collection<?> attributeValues) {
 		super.addAllAttributes(attributeValues);
 		return this;
 	}
 
 	@Override
-	public ExtendedModelMap addAllAttributes(Map<String, ?> attributes) {
+	public ExtendedModelMap addAllAttributes(@Nullable Map<String, ?> attributes) {
 		super.addAllAttributes(attributes);
 		return this;
 	}
 
 	@Override
-	public ExtendedModelMap mergeAttributes(Map<String, ?> attributes) {
+	public ExtendedModelMap mergeAttributes(@Nullable Map<String, ?> attributes) {
 		super.mergeAttributes(attributes);
 		return this;
 	}

spring-context/src/main/java/org/springframework/validation/beanvalidation/MethodValidationPostProcessor.java

@@ -62,6 +62,7 @@ public class MethodValidationPostProcessor extends AbstractBeanFactoryAwareAdvis
 
 	private Class<? extends Annotation> validatedAnnotationType = Validated.class;
 
+	@Nullable
 	private Validator validator;
 
 

spring-context/src/test/java/org/springframework/aop/config/AopNamespaceHandlerTests.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.
@@ -43,9 +43,8 @@ public class AopNamespaceHandlerTests {
 
 
 	@Before
-	public void setUp() {
-		this.context =
-				new ClassPathXmlApplicationContext(getClass().getSimpleName() + "-context.xml", getClass());
+	public void setup() {
+		this.context = new ClassPathXmlApplicationContext(getClass().getSimpleName() + "-context.xml", getClass());
 	}
 
 	protected ITestBean getTestBean() {
@@ -108,7 +107,27 @@ public class AopNamespaceHandlerTests {
 	}
 
 	@Test
-	public void testAspectAppliedForInitializeBean() {
+	public void testAspectAppliedForInitializeBeanWithEmptyName() {
+		ITestBean bean = (ITestBean) this.context.getAutowireCapableBeanFactory().initializeBean(new TestBean(), "");
+
+		CountingAspectJAdvice advice = (CountingAspectJAdvice) this.context.getBean("countingAdvice");
+
+		assertEquals("Incorrect before count", 0, advice.getBeforeCount());
+		assertEquals("Incorrect after count", 0, advice.getAfterCount());
+
+		bean.setName("Sally");
+
+		assertEquals("Incorrect before count", 1, advice.getBeforeCount());
+		assertEquals("Incorrect after count", 1, advice.getAfterCount());
+
+		bean.getName();
+
+		assertEquals("Incorrect before count", 1, advice.getBeforeCount());
+		assertEquals("Incorrect after count", 1, advice.getAfterCount());
+	}
+
+	@Test
+	public void testAspectAppliedForInitializeBeanWithNullName() {
 		ITestBean bean = (ITestBean) this.context.getAutowireCapableBeanFactory().initializeBean(new TestBean(), null);
 
 		CountingAspectJAdvice advice = (CountingAspectJAdvice) this.context.getBean("countingAdvice");
@@ -126,6 +145,7 @@ public class AopNamespaceHandlerTests {
 		assertEquals("Incorrect before count", 1, advice.getBeforeCount());
 		assertEquals("Incorrect after count", 1, advice.getAfterCount());
 	}
+
 }
 
 

spring-core/src/main/java/org/springframework/core/ReactiveAdapterRegistry.java

@@ -30,10 +30,7 @@ import rx.RxReactiveStreams;
 
 import org.springframework.lang.Nullable;
 
-import static org.springframework.core.ReactiveTypeDescriptor.multiValue;
-import static org.springframework.core.ReactiveTypeDescriptor.noValue;
-import static org.springframework.core.ReactiveTypeDescriptor.singleOptionalValue;
-import static org.springframework.core.ReactiveTypeDescriptor.singleRequiredValue;
+import static org.springframework.core.ReactiveTypeDescriptor.*;
 
 /**
  * A registry of adapters to adapt a Reactive Streams {@link Publisher} to/from
@@ -250,7 +247,7 @@ public class ReactiveAdapterRegistry {
 		}
 
 		@Override
-		public <T> Publisher<T> toPublisher(Object source) {
+		public <T> Publisher<T> toPublisher(@Nullable Object source) {
 			Publisher<T> publisher = super.toPublisher(source);
 			return (isMultiValue() ? Flux.from(publisher) : Mono.from(publisher));
 		}

spring-core/src/main/java/org/springframework/core/type/classreading/AnnotationAttributesReadingVisitor.java

@@ -47,7 +47,6 @@ final class AnnotationAttributesReadingVisitor extends RecursiveAnnotationAttrib
 
 	private final MultiValueMap<String, AnnotationAttributes> attributesMap;
 
-	@Nullable
 	private final Map<String, Set<String>> metaAnnotationMap;
 
 
@@ -83,13 +82,11 @@ final class AnnotationAttributesReadingVisitor extends RecursiveAnnotationAttrib
 					}
 				}
 			}
-			if (this.metaAnnotationMap != null) {
-				Set<String> metaAnnotationTypeNames = new LinkedHashSet<>(visited.size());
-				for (Annotation ann : visited) {
-					metaAnnotationTypeNames.add(ann.annotationType().getName());
-				}
-				this.metaAnnotationMap.put(annotationClass.getName(), metaAnnotationTypeNames);
+			Set<String> metaAnnotationTypeNames = new LinkedHashSet<>(visited.size());
+			for (Annotation ann : visited) {
+				metaAnnotationTypeNames.add(ann.annotationType().getName());
 			}
+			this.metaAnnotationMap.put(annotationClass.getName(), metaAnnotationTypeNames);
 		}
 	}
 

spring-core/src/main/java/org/springframework/util/xml/StaxEventXMLReader.java

@@ -66,6 +66,7 @@ class StaxEventXMLReader extends AbstractStaxXMLReader {
 
 	private String xmlVersion = DEFAULT_XML_VERSION;
 
+	@Nullable
 	private String encoding;
 
 
@@ -77,7 +78,7 @@ class StaxEventXMLReader extends AbstractStaxXMLReader {
 	 * @throws IllegalStateException if the reader is not at the start of a document or element
 	 */
 	StaxEventXMLReader(XMLEventReader reader) {
-		Assert.notNull(reader, "'reader' must not be null");
+		Assert.notNull(reader, "XMLEventReader must not be null");
 		try {
 			XMLEvent event = reader.peek();
 			if (event != null && !(event.isStartDocument() || event.isStartElement())) {
@@ -189,6 +190,7 @@ class StaxEventXMLReader extends AbstractStaxXMLReader {
 					return xmlVersion;
 				}
 				@Override
+				@Nullable
 				public String getEncoding() {
 					return encoding;
 				}

spring-core/src/main/java/org/springframework/util/xml/StaxResult.java

@@ -48,31 +48,33 @@ import org.springframework.lang.Nullable;
  */
 class StaxResult extends SAXResult {
 
+	@Nullable
 	private XMLEventWriter eventWriter;
 
+	@Nullable
 	private XMLStreamWriter streamWriter;
 
 
 	/**
-	 * Construct a new instance of the {@code StaxResult} with the specified {@code XMLStreamWriter}.
-	 * @param streamWriter the {@code XMLStreamWriter} to write to
+	 * Construct a new instance of the {@code StaxResult} with the specified {@code XMLEventWriter}.
+	 * @param eventWriter the {@code XMLEventWriter} to write to
 	 */
-	public StaxResult(XMLStreamWriter streamWriter) {
-		StaxStreamHandler handler = new StaxStreamHandler(streamWriter);
+	public StaxResult(XMLEventWriter eventWriter) {
+		StaxEventHandler handler = new StaxEventHandler(eventWriter);
 		super.setHandler(handler);
 		super.setLexicalHandler(handler);
-		this.streamWriter = streamWriter;
+		this.eventWriter = eventWriter;
 	}
 
 	/**
-	 * Construct a new instance of the {@code StaxResult} with the specified {@code XMLEventWriter}.
-	 * @param eventWriter the {@code XMLEventWriter} to write to
+	 * Construct a new instance of the {@code StaxResult} with the specified {@code XMLStreamWriter}.
+	 * @param streamWriter the {@code XMLStreamWriter} to write to
 	 */
-	public StaxResult(XMLEventWriter eventWriter) {
-		StaxEventHandler handler = new StaxEventHandler(eventWriter);
+	public StaxResult(XMLStreamWriter streamWriter) {
+		StaxStreamHandler handler = new StaxStreamHandler(streamWriter);
 		super.setHandler(handler);
 		super.setLexicalHandler(handler);
-		this.eventWriter = eventWriter;
+		this.streamWriter = streamWriter;
 	}
 
 

spring-core/src/main/java/org/springframework/util/xml/StaxSource.java

@@ -47,23 +47,13 @@ import org.springframework.lang.Nullable;
  */
 class StaxSource extends SAXSource {
 
+	@Nullable
 	private XMLEventReader eventReader;
 
+	@Nullable
 	private XMLStreamReader streamReader;
 
 
-	/**
-	 * Construct a new instance of the {@code StaxSource} with the specified {@code XMLStreamReader}.
-	 * The supplied stream reader must be in {@code XMLStreamConstants.START_DOCUMENT} or
-	 * {@code XMLStreamConstants.START_ELEMENT} state.
-	 * @param streamReader the {@code XMLStreamReader} to read from
-	 * @throws IllegalStateException if the reader is not at the start of a document or element
-	 */
-	StaxSource(XMLStreamReader streamReader) {
-		super(new StaxStreamXMLReader(streamReader), new InputSource());
-		this.streamReader = streamReader;
-	}
-
 	/**
 	 * Construct a new instance of the {@code StaxSource} with the specified {@code XMLEventReader}.
 	 * The supplied event reader must be in {@code XMLStreamConstants.START_DOCUMENT} or
@@ -76,6 +66,18 @@ class StaxSource extends SAXSource {
 		this.eventReader = eventReader;
 	}
 
+	/**
+	 * Construct a new instance of the {@code StaxSource} with the specified {@code XMLStreamReader}.
+	 * The supplied stream reader must be in {@code XMLStreamConstants.START_DOCUMENT} or
+	 * {@code XMLStreamConstants.START_ELEMENT} state.
+	 * @param streamReader the {@code XMLStreamReader} to read from
+	 * @throws IllegalStateException if the reader is not at the start of a document or element
+	 */
+	StaxSource(XMLStreamReader streamReader) {
+		super(new StaxStreamXMLReader(streamReader), new InputSource());
+		this.streamReader = streamReader;
+	}
+
 
 	/**
 	 * Return the {@code XMLEventReader} used by this {@code StaxSource}.

spring-core/src/main/java/org/springframework/util/xml/StaxStreamXMLReader.java

@@ -51,6 +51,7 @@ class StaxStreamXMLReader extends AbstractStaxXMLReader {
 
 	private String xmlVersion = DEFAULT_XML_VERSION;
 
+	@Nullable
 	private String encoding;
 
 
@@ -62,7 +63,7 @@ class StaxStreamXMLReader extends AbstractStaxXMLReader {
 	 * @throws IllegalStateException if the reader is not at the start of a document or element
 	 */
 	StaxStreamXMLReader(XMLStreamReader reader) {
-		Assert.notNull(reader, "'reader' must not be null");
+		Assert.notNull(reader, "XMLStreamReader must not be null");
 		int event = reader.getEventType();
 		if (!(event == XMLStreamConstants.START_DOCUMENT || event == XMLStreamConstants.START_ELEMENT)) {
 			throw new IllegalStateException("XMLEventReader not at start of document or element");
@@ -166,6 +167,7 @@ class StaxStreamXMLReader extends AbstractStaxXMLReader {
 					return xmlVersion;
 				}
 				@Override
+				@Nullable
 				public String getEncoding() {
 					return encoding;
 				}

spring-expression/src/main/java/org/springframework/expression/spel/ast/CompoundExpression.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.
@@ -22,6 +22,7 @@ import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.CodeFlow;
 import org.springframework.expression.spel.ExpressionState;
 import org.springframework.expression.spel.SpelEvaluationException;
+import org.springframework.lang.Nullable;
 
 /**
  * Represents a DOT separated expression sequence, such as 'property1.property2.methodOne()'
@@ -91,7 +92,7 @@ public class CompoundExpression extends SpelNodeImpl {
 	}
 
 	@Override
-	public void setValue(ExpressionState state, Object value) throws EvaluationException {
+	public void setValue(ExpressionState state, @Nullable Object value) throws EvaluationException {
 		getValueRef(state).setValue(value);
 	}
 

spring-expression/src/main/java/org/springframework/expression/spel/ast/OperatorInstanceof.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.
@@ -25,7 +25,8 @@ import org.springframework.expression.spel.ExpressionState;
 import org.springframework.expression.spel.SpelEvaluationException;
 import org.springframework.expression.spel.SpelMessage;
 import org.springframework.expression.spel.support.BooleanTypedValue;
-
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * The operator 'instanceof' checks if an object is of the class specified in the right
@@ -36,8 +37,10 @@ import org.springframework.expression.spel.support.BooleanTypedValue;
  */
 public class OperatorInstanceof extends Operator {
 
+	@Nullable
 	private Class<?> type;
 	
+
 	public OperatorInstanceof(int pos, SpelNodeImpl... operands) {
 		super("instanceof", pos, operands);
 	}
@@ -47,8 +50,8 @@ public class OperatorInstanceof extends Operator {
 	 * Compare the left operand to see it is an instance of the type specified as the
 	 * right operand. The right operand must be a class.
 	 * @param state the expression state
-	 * @return true if the left operand is an instanceof of the right operand, otherwise
-	 *         false
+	 * @return {@code true} if the left operand is an instanceof of the right operand,
+	 * otherwise {@code false}
 	 * @throws EvaluationException if there is a problem evaluating the expression
 	 */
 	@Override
@@ -58,7 +61,7 @@ public class OperatorInstanceof extends Operator {
 		TypedValue right = rightOperand.getValueInternal(state);
 		Object leftValue = left.getValue();
 		Object rightValue = right.getValue();
-		BooleanTypedValue result = null;
+		BooleanTypedValue result;
 		if (rightValue == null || !(rightValue instanceof Class)) {
 			throw new SpelEvaluationException(getRightOperand().getStartPosition(),
 					SpelMessage.INSTANCEOF_OPERATOR_NEEDS_CLASS_OPERAND,
@@ -89,6 +92,7 @@ public class OperatorInstanceof extends Operator {
 	public void generateCode(MethodVisitor mv, CodeFlow cf) {
 		getLeftOperand().generateCode(mv, cf);
 		CodeFlow.insertBoxIfNecessary(mv, cf.lastDescriptor());
+		Assert.state(this.type != null, "No type available");
 		if (this.type.isPrimitive()) {
 			// always false - but left operand code always driven
 			// in case it had side effects
@@ -96,7 +100,7 @@ public class OperatorInstanceof extends Operator {
 			mv.visitInsn(ICONST_0); // value of false
 		} 
 		else {
-			mv.visitTypeInsn(INSTANCEOF,Type.getInternalName(this.type));
+			mv.visitTypeInsn(INSTANCEOF, Type.getInternalName(this.type));
 		}
 		cf.pushDescriptor(this.exitTypeDescriptor);
 	}

spring-expression/src/main/java/org/springframework/expression/spel/ast/TypeReference.java

@@ -24,6 +24,7 @@ import org.springframework.expression.EvaluationException;
 import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.CodeFlow;
 import org.springframework.expression.spel.ExpressionState;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -35,15 +36,16 @@ public class TypeReference extends SpelNodeImpl {
 
 	private final int dimensions;
 
+	@Nullable
 	private transient Class<?> type;
 
 
 	public TypeReference(int pos, SpelNodeImpl qualifiedId) {
-		this(pos,qualifiedId,0);
+		this(pos, qualifiedId, 0);
 	}
 
 	public TypeReference(int pos, SpelNodeImpl qualifiedId, int dims) {
-		super(pos,qualifiedId);
+		super(pos, qualifiedId);
 		this.dimensions = dims;
 	}
 
@@ -99,6 +101,7 @@ public class TypeReference extends SpelNodeImpl {
 	@Override
 	public void generateCode(MethodVisitor mv, CodeFlow cf) {
 		// TODO Future optimization - if followed by a static method call, skip generating code here
+		Assert.state(this.type != null, "No type available");
 		if (this.type.isPrimitive()) {
 			if (this.type == Integer.TYPE) {
 				mv.visitFieldInsn(GETSTATIC, "java/lang/Integer", "TYPE", "Ljava/lang/Class;");

spring-expression/src/main/java/org/springframework/expression/spel/ast/ValueRef.java

@@ -68,7 +68,7 @@ public interface ValueRef {
 		}
 
 		@Override
-		public void setValue(Object newValue) {
+		public void setValue(@Nullable Object newValue) {
 			// The exception position '0' isn't right but the overhead of creating
 			// instances of this per node (where the node is solely for error reporting)
 			// would be unfortunate.
@@ -102,7 +102,7 @@ public interface ValueRef {
 		}
 
 		@Override
-		public void setValue(Object newValue) {
+		public void setValue(@Nullable Object newValue) {
 			throw new SpelEvaluationException(this.node.pos, SpelMessage.NOT_ASSIGNABLE, this.node.toStringAST());
 		}
 

spring-expression/src/main/java/org/springframework/expression/spel/support/StandardEvaluationContext.java

@@ -157,6 +157,7 @@ public class StandardEvaluationContext implements EvaluationContext {
 	}
 
 	@Override
+	@Nullable
 	public BeanResolver getBeanResolver() {
 		return this.beanResolver;
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/InvalidResultSetAccessException.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.
@@ -19,6 +19,7 @@ package org.springframework.jdbc;
 import java.sql.SQLException;
 
 import org.springframework.dao.InvalidDataAccessResourceUsageException;
+import org.springframework.lang.Nullable;
 
 /**
  * Exception thrown when a ResultSet has been accessed in an invalid fashion.
@@ -35,6 +36,7 @@ import org.springframework.dao.InvalidDataAccessResourceUsageException;
 @SuppressWarnings("serial")
 public class InvalidResultSetAccessException extends InvalidDataAccessResourceUsageException {
 
+	@Nullable
 	private String sql;
 
 
@@ -69,6 +71,7 @@ public class InvalidResultSetAccessException extends InvalidDataAccessResourceUs
 	 * Return the SQL that caused the problem.
 	 * @return the offending SQL, if known
 	 */
+	@Nullable
 	public String getSql() {
 		return this.sql;
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java

@@ -515,6 +515,7 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 
 		class BatchUpdateStatementCallback implements StatementCallback<int[]>, SqlProvider {
 
+			@Nullable
 			private String currSql;
 
 			@Override

spring-jdbc/src/main/java/org/springframework/jdbc/core/RowCountCallbackHandler.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.
@@ -21,6 +21,7 @@ import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 
 import org.springframework.jdbc.support.JdbcUtils;
+import org.springframework.lang.Nullable;
 
 /**
  * Implementation of RowCallbackHandler. Convenient superclass for callback handlers.
@@ -54,11 +55,13 @@ public class RowCountCallbackHandler implements RowCallbackHandler {
 	 * Indexed from 0. Type (as in java.sql.Types) for the columns
 	 * as returned by ResultSetMetaData object.
 	 */
+	@Nullable
 	private int[] columnTypes;
 
 	/**
 	 * Indexed from 0. Column name as returned by ResultSetMetaData object.
 	 */
+	@Nullable
 	private String[] columnNames;
 
 
@@ -102,8 +105,9 @@ public class RowCountCallbackHandler implements RowCallbackHandler {
 	 * @return the types of the columns as java.sql.Types constants.
 	 * <b>Indexed from 0 to n-1.</b>
 	 */
+	@Nullable
 	public final int[] getColumnTypes() {
-		return columnTypes;
+		return this.columnTypes;
 	}
 
 	/**
@@ -112,8 +116,9 @@ public class RowCountCallbackHandler implements RowCallbackHandler {
 	 * @return the names of the columns.
 	 * <b>Indexed from 0 to n-1.</b>
 	 */
+	@Nullable
 	public final String[] getColumnNames() {
-		return columnNames;
+		return this.columnNames;
 	}
 
 	/**
@@ -122,7 +127,7 @@ public class RowCountCallbackHandler implements RowCallbackHandler {
 	 * @return the number of rows in this ResultSet
 	 */
 	public final int getRowCount() {
-		return rowCount;
+		return this.rowCount;
 	}
 
 	/**
@@ -132,7 +137,7 @@ public class RowCountCallbackHandler implements RowCallbackHandler {
 	 * @return the number of columns in this result set
 	 */
 	public final int getColumnCount() {
-		return columnCount;
+		return this.columnCount;
 	}
 
 }

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/GenericCallMetaDataProvider.java

@@ -107,7 +107,7 @@ public class GenericCallMetaDataProvider implements CallMetaDataProvider {
 
 	@Override
 	public void initializeWithProcedureColumnMetaData(DatabaseMetaData databaseMetaData, @Nullable String catalogName,
-			@Nullable String schemaName, String procedureName) throws SQLException {
+			@Nullable String schemaName, @Nullable String procedureName) throws SQLException {
 
 		this.procedureColumnMetaDataUsed = true;
 		processProcedureColumns(databaseMetaData, catalogName, schemaName,  procedureName);

spring-jdbc/src/main/java/org/springframework/jdbc/core/simple/AbstractJdbcCall.java

@@ -71,12 +71,14 @@ public abstract class AbstractJdbcCall {
 	private volatile boolean compiled = false;
 
 	/** The generated string used for call statement */
+	@Nullable
 	private String callString;
 
 	/**
 	 * A delegate enabling us to create CallableStatementCreators
 	 * efficiently, based on this class's declared parameters.
 	 */
+	@Nullable
 	private CallableStatementCreatorFactory callableStatementFactory;
 
 
@@ -222,6 +224,7 @@ public abstract class AbstractJdbcCall {
 	/**
 	 * Get the call string that should be used based on parameters and meta data.
 	 */
+	@Nullable
 	public String getCallString() {
 		return this.callString;
 	}
@@ -230,6 +233,7 @@ public abstract class AbstractJdbcCall {
 	 * Get the {@link CallableStatementCreatorFactory} being used
 	 */
 	protected CallableStatementCreatorFactory getCallableStatementFactory() {
+		Assert.state(this.callableStatementFactory != null, "No CallableStatementCreatorFactory available");
 		return this.callableStatementFactory;
 	}
 
@@ -322,7 +326,7 @@ public abstract class AbstractJdbcCall {
 		}
 
 		this.callableStatementFactory =
-				new CallableStatementCreatorFactory(getCallString(), this.callMetaDataContext.getCallParameters());
+				new CallableStatementCreatorFactory(this.callString, this.callMetaDataContext.getCallParameters());
 
 		onCompileInternal();
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/core/simple/AbstractJdbcInsert.java

@@ -81,9 +81,11 @@ public abstract class AbstractJdbcInsert {
 	private volatile boolean compiled = false;
 
 	/** The generated string used for insert statement */
+	@Nullable
 	private String insertString;
 
 	/** The SQL type information for the insert columns */
+	@Nullable
 	private int[] insertTypes;
 
 
@@ -222,6 +224,7 @@ public abstract class AbstractJdbcInsert {
 	/**
 	 * Get the insert string to be used.
 	 */
+	@Nullable
 	public String getInsertString() {
 		return this.insertString;
 	}
@@ -229,6 +232,7 @@ public abstract class AbstractJdbcInsert {
 	/**
 	 * Get the array of {@link java.sql.Types} to be used for insert.
 	 */
+	@Nullable
 	public int[] getInsertTypes() {
 		return this.insertTypes;
 	}
@@ -276,7 +280,7 @@ public abstract class AbstractJdbcInsert {
 		this.insertString = this.tableMetaDataContext.createInsertString(getGeneratedKeyNames());
 		this.insertTypes = this.tableMetaDataContext.createInsertTypes();
 		if (logger.isDebugEnabled()) {
-			logger.debug("Compiled insert object: insert string is [" + getInsertString() + "]");
+			logger.debug("Compiled insert object: insert string is [" + this.insertString + "]");
 		}
 		onCompileInternal();
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/core/support/JdbcBeanDefinitionReader.java

@@ -22,6 +22,7 @@ import javax.sql.DataSource;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.PropertiesBeanDefinitionReader;
 import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -45,6 +46,7 @@ public class JdbcBeanDefinitionReader {
 
 	private final PropertiesBeanDefinitionReader propReader;
 
+	@Nullable
 	private JdbcTemplate jdbcTemplate;
 
 

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/IsolationLevelDataSourceAdapter.java

@@ -126,7 +126,7 @@ public class IsolationLevelDataSourceAdapter extends UserCredentialsDataSourceAd
 	 * @see #getCurrentReadOnlyFlag()
 	 */
 	@Override
-	protected Connection doGetConnection(String username, String password) throws SQLException {
+	protected Connection doGetConnection(@Nullable String username, @Nullable String password) throws SQLException {
 		Connection con = super.doGetConnection(username, password);
 		Boolean readOnlyToUse = getCurrentReadOnlyFlag();
 		if (readOnlyToUse != null) {

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/SimpleDriverDataSource.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.
@@ -22,6 +22,7 @@ import java.sql.SQLException;
 import java.util.Properties;
 
 import org.springframework.beans.BeanUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -52,6 +53,7 @@ import org.springframework.util.Assert;
  */
 public class SimpleDriverDataSource extends AbstractDriverBasedDataSource {
 
+	@Nullable
 	private Driver driver;
 
 
@@ -117,13 +119,14 @@ public class SimpleDriverDataSource extends AbstractDriverBasedDataSource {
 	 * Driver instance.
 	 * @see #setDriverClass
 	 */
-	public void setDriver(Driver driver) {
+	public void setDriver(@Nullable Driver driver) {
 		this.driver = driver;
 	}
 
 	/**
 	 * Return the JDBC Driver instance to use.
 	 */
+	@Nullable
 	public Driver getDriver() {
 		return this.driver;
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/WebSphereDataSourceAdapter.java

@@ -132,7 +132,7 @@ public class WebSphereDataSourceAdapter extends IsolationLevelDataSourceAdapter
 	 * @see com.ibm.websphere.rsadapter.WSDataSource#getConnection(com.ibm.websphere.rsadapter.JDBCConnectionSpec)
 	 */
 	@Override
-	protected Connection doGetConnection(String username, String password) throws SQLException {
+	protected Connection doGetConnection(@Nullable String username, @Nullable String password) throws SQLException {
 		// Create JDBCConnectionSpec using current isolation level value and read-only flag.
 		Object connSpec = createConnectionSpec(
 				getCurrentIsolationLevel(), getCurrentReadOnlyFlag(), username, password);

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/init/DataSourceInitializer.java

@@ -38,8 +38,10 @@ public class DataSourceInitializer implements InitializingBean, DisposableBean {
 	@Nullable
 	private DataSource dataSource;
 
+	@Nullable
 	private DatabasePopulator databasePopulator;
 
+	@Nullable
 	private DatabasePopulator databaseCleaner;
 
 	private boolean enabled = true;

spring-jdbc/src/main/java/org/springframework/jdbc/support/xml/Jdbc4SqlXmlHandler.java

@@ -171,6 +171,7 @@ public class Jdbc4SqlXmlHandler implements SqlXmlHandler {
 	 */
 	private static abstract class AbstractJdbc4SqlXmlValue implements SqlXmlValue {
 
+		@Nullable
 		private SQLXML xmlObject;
 
 		@Override
@@ -187,11 +188,13 @@ public class Jdbc4SqlXmlHandler implements SqlXmlHandler {
 
 		@Override
 		public void cleanup() {
-			try {
-				this.xmlObject.free();
-			}
-			catch (SQLException ex) {
-				throw new DataAccessResourceFailureException("Could not free SQLXML object", ex);
+			if (this.xmlObject != null) {
+				try {
+					this.xmlObject.free();
+				}
+				catch (SQLException ex) {
+					throw new DataAccessResourceFailureException("Could not free SQLXML object", ex);
+				}
 			}
 		}
 

spring-jms/src/main/java/org/springframework/jms/listener/AbstractMessageListenerContainer.java

@@ -31,7 +31,6 @@ import org.springframework.jms.support.JmsUtils;
 import org.springframework.jms.support.QosSettings;
 import org.springframework.jms.support.converter.MessageConverter;
 import org.springframework.lang.Nullable;
-import org.springframework.util.Assert;
 import org.springframework.util.ErrorHandler;
 
 /**
@@ -506,6 +505,7 @@ public abstract class AbstractMessageListenerContainer extends AbstractJmsListen
 	}
 
 	@Override
+	@Nullable
 	public QosSettings getReplyQosSettings() {
 		return this.replyQosSettings;
 	}
@@ -514,11 +514,12 @@ public abstract class AbstractMessageListenerContainer extends AbstractJmsListen
 	 * Set the {@link MessageConverter} strategy for converting JMS Messages.
 	 * @since 4.1
 	 */
-	public void setMessageConverter(MessageConverter messageConverter) {
+	public void setMessageConverter(@Nullable MessageConverter messageConverter) {
 		this.messageConverter = messageConverter;
 	}
 
 	@Override
+	@Nullable
 	public MessageConverter getMessageConverter() {
 		return this.messageConverter;
 	}

spring-jms/src/main/java/org/springframework/jms/listener/adapter/MessageListenerAdapter.java

@@ -144,7 +144,8 @@ public class MessageListenerAdapter extends AbstractAdaptableMessageListener imp
 	 * @param delegate the delegate object
 	 */
 	public MessageListenerAdapter(Object delegate) {
-		setDelegate(delegate);
+		Assert.notNull(delegate, "Delegate must not be null");
+		this.delegate = delegate;
 	}
 
 
@@ -196,12 +197,13 @@ public class MessageListenerAdapter extends AbstractAdaptableMessageListener imp
 	 */
 	@Override
 	@SuppressWarnings("unchecked")
-	public void onMessage(Message message, Session session) throws JMSException {
+	public void onMessage(Message message, @Nullable Session session) throws JMSException {
 		// Check whether the delegate is a MessageListener impl itself.
 		// In that case, the adapter will simply act as a pass-through.
 		Object delegate = getDelegate();
 		if (delegate != this) {
 			if (delegate instanceof SessionAwareMessageListener) {
+				Assert.state(session != null, "Session is required for SessionAwareMessageListener");
 				((SessionAwareMessageListener<Message>) delegate).onMessage(message, session);
 				return;
 			}

spring-jms/src/main/java/org/springframework/jms/listener/adapter/MessagingMessageListenerAdapter.java

@@ -28,6 +28,7 @@ import org.springframework.messaging.MessagingException;
 import org.springframework.messaging.core.AbstractMessageSendingTemplate;
 import org.springframework.messaging.handler.invocation.InvocableHandlerMethod;
 import org.springframework.messaging.support.MessageBuilder;
+import org.springframework.util.Assert;
 
 /**
  * A {@link javax.jms.MessageListener} adapter that invokes a configurable
@@ -49,6 +50,7 @@ import org.springframework.messaging.support.MessageBuilder;
  */
 public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageListener {
 
+	@Nullable
 	private InvocableHandlerMethod handlerMethod;
 
 
@@ -60,9 +62,14 @@ public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageLis
 		this.handlerMethod = handlerMethod;
 	}
 
+	private InvocableHandlerMethod getHandlerMethod() {
+		Assert.state(this.handlerMethod != null, "No HandlerMethod set");
+		return this.handlerMethod;
+	}
+
 
 	@Override
-	public void onMessage(javax.jms.Message jmsMessage, Session session) throws JMSException {
+	public void onMessage(javax.jms.Message jmsMessage, @Nullable Session session) throws JMSException {
 		Message<?> message = toMessagingMessage(jmsMessage);
 		if (logger.isDebugEnabled()) {
 			logger.debug("Processing [" + message + "]");
@@ -78,7 +85,7 @@ public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageLis
 
 	@Override
 	protected Object preProcessResponse(Object result) {
-		MethodParameter returnType = this.handlerMethod.getReturnType();
+		MethodParameter returnType = getHandlerMethod().getReturnType();
 		if (result instanceof Message) {
 			return MessageBuilder.fromMessage((Message<?>) result)
 					.setHeader(AbstractMessageSendingTemplate.CONVERSION_HINT_HEADER, returnType).build();
@@ -101,9 +108,10 @@ public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageLis
 	 * with a dedicated error message.
 	 */
 	@Nullable
-	private Object invokeHandler(javax.jms.Message jmsMessage, Session session, Message<?> message) {
+	private Object invokeHandler(javax.jms.Message jmsMessage, @Nullable Session session, Message<?> message) {
+		InvocableHandlerMethod handlerMethod = getHandlerMethod();
 		try {
-			return this.handlerMethod.invoke(message, jmsMessage, session);
+			return handlerMethod.invoke(message, jmsMessage, session);
 		}
 		catch (MessagingException ex) {
 			throw new ListenerExecutionFailedException(
@@ -111,15 +119,16 @@ public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageLis
 		}
 		catch (Exception ex) {
 			throw new ListenerExecutionFailedException("Listener method '" +
-					this.handlerMethod.getMethod().toGenericString() + "' threw exception", ex);
+					handlerMethod.getMethod().toGenericString() + "' threw exception", ex);
 		}
 	}
 
 	private String createMessagingErrorMessage(String description) {
+		InvocableHandlerMethod handlerMethod = getHandlerMethod();
 		StringBuilder sb = new StringBuilder(description).append("\n")
 				.append("Endpoint handler details:\n")
-				.append("Method [").append(this.handlerMethod.getMethod()).append("]\n")
-				.append("Bean [").append(this.handlerMethod.getBean()).append("]\n");
+				.append("Method [").append(handlerMethod.getMethod()).append("]\n")
+				.append("Bean [").append(handlerMethod.getBean()).append("]\n");
 		return sb.toString();
 	}
 

spring-jms/src/main/java/org/springframework/jms/listener/endpoint/JmsMessageEndpointFactory.java

@@ -22,6 +22,8 @@ import javax.resource.ResourceException;
 import javax.resource.spi.UnavailableException;
 
 import org.springframework.jca.endpoint.AbstractMessageEndpointFactory;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * JMS-specific implementation of the JCA 1.7
@@ -47,6 +49,7 @@ import org.springframework.jca.endpoint.AbstractMessageEndpointFactory;
  */
 public class JmsMessageEndpointFactory extends AbstractMessageEndpointFactory  {
 
+	@Nullable
 	private MessageListener messageListener;
 
 
@@ -61,6 +64,7 @@ public class JmsMessageEndpointFactory extends AbstractMessageEndpointFactory  {
 	 * Return the JMS MessageListener for this endpoint.
 	 */
 	protected MessageListener getMessageListener() {
+		Assert.state(messageListener != null, "No MessageListener set");
 		return this.messageListener;
 	}
 
@@ -90,16 +94,12 @@ public class JmsMessageEndpointFactory extends AbstractMessageEndpointFactory  {
 				}
 			}
 			try {
-				messageListener.onMessage(message);
+				getMessageListener().onMessage(message);
 			}
-			catch (RuntimeException ex) {
+			catch (RuntimeException | Error ex) {
 				onEndpointException(ex);
 				throw ex;
 			}
-			catch (Error err) {
-				onEndpointException(err);
-				throw err;
-			}
 			finally {
 				if (applyDeliveryCalls) {
 					try {
@@ -114,7 +114,7 @@ public class JmsMessageEndpointFactory extends AbstractMessageEndpointFactory  {
 
 		@Override
 		protected ClassLoader getEndpointClassLoader() {
-			return messageListener.getClass().getClassLoader();
+			return getMessageListener().getClass().getClassLoader();
 		}
 	}
 

spring-jms/src/main/java/org/springframework/jms/remoting/JmsInvokerServiceExporter.java

@@ -59,6 +59,7 @@ public class JmsInvokerServiceExporter extends RemoteInvocationBasedExporter
 
 	private boolean ignoreInvalidRequests = true;
 
+	@Nullable
 	private Object proxy;
 
 

spring-jms/src/main/java/org/springframework/jms/support/converter/MarshallingMessageConverter.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.
@@ -32,6 +32,7 @@ import javax.xml.transform.stream.StreamResult;
 import javax.xml.transform.stream.StreamSource;
 
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
 import org.springframework.oxm.Marshaller;
 import org.springframework.oxm.Unmarshaller;
 import org.springframework.oxm.XmlMappingException;
@@ -51,8 +52,10 @@ import org.springframework.util.Assert;
  */
 public class MarshallingMessageConverter implements MessageConverter, InitializingBean {
 
+	@Nullable
 	private Marshaller marshaller;
 
+	@Nullable
 	private Unmarshaller unmarshaller;
 
 	private MessageType targetType = MessageType.BYTES;
@@ -108,6 +111,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 	 * Set the {@link Marshaller} to be used by this message converter.
 	 */
 	public void setMarshaller(Marshaller marshaller) {
+		Assert.notNull(marshaller, "Marshaller must not be null");
 		this.marshaller = marshaller;
 	}
 
@@ -115,6 +119,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 	 * Set the {@link Unmarshaller} to be used by this message converter.
 	 */
 	public void setUnmarshaller(Unmarshaller unmarshaller) {
+		Assert.notNull(unmarshaller, "Unmarshaller must not be null");
 		this.unmarshaller = unmarshaller;
 	}
 
@@ -148,6 +153,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 	 */
 	@Override
 	public Message toMessage(Object object, Session session) throws JMSException, MessageConversionException {
+		Assert.state(this.marshaller != null, "No Marshaller set");
 		try {
 			switch (this.targetType) {
 				case TEXT:
@@ -158,10 +164,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 					return marshalToMessage(object, session, this.marshaller, this.targetType);
 			}
 		}
-		catch (XmlMappingException ex) {
-			throw new MessageConversionException("Could not marshal [" + object + "]", ex);
-		}
-		catch (IOException ex) {
+		catch (XmlMappingException | IOException ex) {
 			throw new MessageConversionException("Could not marshal [" + object + "]", ex);
 		}
 	}
@@ -173,6 +176,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 	 */
 	@Override
 	public Object fromMessage(Message message) throws JMSException, MessageConversionException {
+		Assert.state(this.unmarshaller != null, "No Unmarshaller set");
 		try {
 			if (message instanceof TextMessage) {
 				TextMessage textMessage = (TextMessage) message;

spring-messaging/src/main/java/org/springframework/messaging/converter/DefaultContentTypeResolver.java

@@ -32,6 +32,7 @@ import org.springframework.util.MimeType;
  */
 public class DefaultContentTypeResolver implements ContentTypeResolver {
 
+	@Nullable
 	private MimeType defaultMimeType;
 
 
@@ -40,7 +41,7 @@ public class DefaultContentTypeResolver implements ContentTypeResolver {
 	 * {@link MessageHeaders#CONTENT_TYPE} header present.
 	 * <p>This property does not have a default value.
 	 */
-	public void setDefaultMimeType(MimeType defaultMimeType) {
+	public void setDefaultMimeType(@Nullable MimeType defaultMimeType) {
 		this.defaultMimeType = defaultMimeType;
 	}
 
@@ -48,6 +49,7 @@ public class DefaultContentTypeResolver implements ContentTypeResolver {
 	 * Return the default MIME type to use if no
 	 * {@link MessageHeaders#CONTENT_TYPE} header is present.
 	 */
+	@Nullable
 	public MimeType getDefaultMimeType() {
 		return this.defaultMimeType;
 	}

spring-messaging/src/main/java/org/springframework/messaging/core/GenericMessagingTemplate.java

@@ -276,6 +276,7 @@ public class GenericMessagingTemplate extends AbstractDestinationResolvingMessag
 
 		private final boolean throwExceptionOnLateReply;
 
+		@Nullable
 		private volatile Message<?> replyMessage;
 
 		private volatile boolean hasReceived;

spring-messaging/src/main/java/org/springframework/messaging/simp/broker/AbstractBrokerMessageHandler.java

@@ -283,7 +283,9 @@ public abstract class AbstractBrokerMessageHandler
 	private class UnsentDisconnectChannelInterceptor extends ChannelInterceptorAdapter {
 
 		@Override
-		public void afterSendCompletion(Message<?> message, MessageChannel channel, boolean sent, Exception ex) {
+		public void afterSendCompletion(
+				Message<?> message, MessageChannel channel, boolean sent, @Nullable Exception ex) {
+
 			if (!sent) {
 				SimpMessageType messageType = SimpMessageHeaderAccessor.getMessageType(message.getHeaders());
 				if (SimpMessageType.DISCONNECT.equals(messageType)) {

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java

@@ -548,6 +548,7 @@ public class DefaultStompSession implements ConnectionHandlingStompSession {
 		}
 
 		@Override
+		@Nullable
 		public String getReceiptId() {
 			return this.receiptId;
 		}

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompHeaderAccessor.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.
@@ -256,7 +256,7 @@ public class StompHeaderAccessor extends SimpMessageHeaderAccessor {
 	}
 
 	@Override
-	public void setDestination(String destination) {
+	public void setDestination(@Nullable String destination) {
 		super.setDestination(destination);
 		setNativeHeader(STOMP_DESTINATION_HEADER, destination);
 	}

spring-messaging/src/main/java/org/springframework/messaging/simp/user/MultiServerUserRegistry.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.
@@ -18,6 +18,7 @@ package org.springframework.messaging.simp.user;
 
 import java.net.InetAddress;
 import java.net.UnknownHostException;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -195,9 +196,9 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 	 */
 	private static class UserRegistrySnapshot {
 
-		private String id;
+		private String id = "";
 
-		private Map<String, TransferSimpUser> users;
+		private Map<String, TransferSimpUser> users = Collections.emptyMap();
 
 		private long expirationTime;
 
@@ -273,12 +274,12 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 	 */
 	private static class TransferSimpUser implements SimpUser {
 
-		private String name;
+		private String name = "";
 
-		/* User sessions from "this" registry only (i.e. one server) */
+		// User sessions from "this" registry only (i.e. one server)
 		private Set<TransferSimpSession> sessions;
 
-		/* Cross-server session lookup (e.g. user connected to multiple servers) */
+		// Cross-server session lookup (e.g. user connected to multiple servers)
 		@Nullable
 		private SessionLookup sessionLookup;
 
@@ -393,6 +394,8 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 		 */
 		@SuppressWarnings("unused")
 		public TransferSimpSession() {
+			this.id = "";
+			this.user = new TransferSimpUser();
 			this.subscriptions = new HashSet<>(4);
 		}
 
@@ -401,6 +404,7 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 		 */
 		public TransferSimpSession(SimpSession session) {
 			this.id = session.getId();
+			this.user = new TransferSimpUser();
 			Set<SimpSubscription> subscriptions = session.getSubscriptions();
 			this.subscriptions = new HashSet<>(subscriptions.size());
 			for (SimpSubscription subscription : subscriptions) {
@@ -443,12 +447,12 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 
 		@Override
 		public boolean equals(Object other) {
-			return (this == other || (other instanceof SimpSession && this.id.equals(((SimpSession) other).getId())));
+			return (this == other || (other instanceof SimpSession && getId().equals(((SimpSession) other).getId())));
 		}
 
 		@Override
 		public int hashCode() {
-			return this.id.hashCode();
+			return getId().hashCode();
 		}
 
 		@Override
@@ -474,6 +478,9 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 		 */
 		@SuppressWarnings("unused")
 		public TransferSimpSubscription() {
+			this.id = "";
+			this.session = new TransferSimpSession();
+			this.destination = "";
 		}
 
 		/**
@@ -481,6 +488,7 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 		 */
 		public TransferSimpSubscription(SimpSubscription subscription) {
 			this.id = subscription.getId();
+			this.session = new TransferSimpSession();
 			this.destination = subscription.getDestination();
 		}
 
@@ -520,13 +528,13 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 				return false;
 			}
 			SimpSubscription otherSubscription = (SimpSubscription) other;
-			return (ObjectUtils.nullSafeEquals(getSession(), otherSubscription.getSession()) &&
-					this.id.equals(otherSubscription.getId()));
+			return (getId().equals(otherSubscription.getId()) &&
+					ObjectUtils.nullSafeEquals(getSession(), otherSubscription.getSession()));
 		}
 
 		@Override
 		public int hashCode() {
-			return this.id.hashCode() * 31 + ObjectUtils.nullSafeHashCode(getSession());
+			return getId().hashCode() * 31 + ObjectUtils.nullSafeHashCode(getSession());
 		}
 
 		@Override

spring-messaging/src/main/java/org/springframework/messaging/simp/user/SimpSession.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.
@@ -18,6 +18,8 @@ package org.springframework.messaging.simp.user;
 
 import java.util.Set;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Represents a session of connected user.
  *

spring-messaging/src/main/java/org/springframework/messaging/simp/user/SimpSubscription.java

@@ -16,6 +16,8 @@
 
 package org.springframework.messaging.simp.user;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Represents a subscription within a user session.
  *
@@ -25,17 +27,17 @@ package org.springframework.messaging.simp.user;
 public interface SimpSubscription {
 
 	/**
-	 * Return the id associated of the subscription (never {@code null}).
+	 * Return the id associated of the subscription.
 	 */
 	String getId();
 
 	/**
-	 * Return the session of the subscription (never {@code null}).
+	 * Return the session of the subscription.
 	 */
 	SimpSession getSession();
 
 	/**
-	 * Return the subscription's destination (never {@code null}).
+	 * Return the subscription's destination.
 	 */
 	String getDestination();
 

spring-messaging/src/main/java/org/springframework/messaging/support/ChannelInterceptorAdapter.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.
@@ -16,6 +16,7 @@
 
 package org.springframework.messaging.support;
 
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageChannel;
 
@@ -39,7 +40,7 @@ public abstract class ChannelInterceptorAdapter implements ChannelInterceptor {
 	}
 
 	@Override
-	public void afterSendCompletion(Message<?> message, MessageChannel channel, boolean sent, Exception ex) {
+	public void afterSendCompletion(Message<?> message, MessageChannel channel, boolean sent, @Nullable Exception ex) {
 	}
 
 	public boolean preReceive(MessageChannel channel) {
@@ -52,7 +53,7 @@ public abstract class ChannelInterceptorAdapter implements ChannelInterceptor {
 	}
 
 	@Override
-	public void afterReceiveCompletion(Message<?> message, MessageChannel channel, Exception ex) {
+	public void afterReceiveCompletion(@Nullable Message<?> message, MessageChannel channel, @Nullable Exception ex) {
 	}
 
 }

spring-messaging/src/test/java/org/springframework/messaging/simp/user/MultiServerUserRegistryTests.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.
@@ -49,7 +49,7 @@ public class MultiServerUserRegistryTests {
 
 
 	@Before
-	public void setUp() throws Exception {
+	public void setup() throws Exception {
 		this.localRegistry = Mockito.mock(SimpUserRegistry.class);
 		this.registry = new MultiServerUserRegistry(this.localRegistry);
 		this.converter = new MappingJackson2MessageConverter();
@@ -70,7 +70,6 @@ public class MultiServerUserRegistryTests {
 
 	@Test
 	public void getUserFromRemoteRegistry() throws Exception {
-
 		// Prepare broadcast message from remote server
 		TestSimpUser testUser = new TestSimpUser("joe");
 		TestSimpSession testSession = new TestSimpSession("remote-sess");
@@ -84,7 +83,6 @@ public class MultiServerUserRegistryTests {
 		// Add remote registry
 		this.registry.addRemoteRegistryDto(message, this.converter, 20000);
 
-
 		assertEquals(1, this.registry.getUserCount());
 		SimpUser user = this.registry.getUser("joe");
 		assertNotNull(user);
@@ -103,7 +101,6 @@ public class MultiServerUserRegistryTests {
 
 	@Test
 	public void findSubscriptionsFromRemoteRegistry() throws Exception {
-
 		// Prepare broadcast message from remote server
 		TestSimpUser user1 = new TestSimpUser("joe");
 		TestSimpUser user2 = new TestSimpUser("jane");
@@ -125,7 +122,6 @@ public class MultiServerUserRegistryTests {
 		// Add remote registry
 		this.registry.addRemoteRegistryDto(message, this.converter, 20000);
 
-
 		assertEquals(3, this.registry.getUserCount());
 		Set<SimpSubscription> matches = this.registry.findSubscriptions(s -> s.getDestination().equals("/match"));
 		assertEquals(2, matches.size());
@@ -136,9 +132,8 @@ public class MultiServerUserRegistryTests {
 		assertEquals(new HashSet<>(Arrays.asList("sess1", "sess2")), sessionIds);
 	}
 
-	@Test // SPR-13800
+	@Test  // SPR-13800
 	public void getSessionsWhenUserIsConnectedToMultipleServers() throws Exception {
-
 		// Add user to local registry
 		TestSimpUser localUser = new TestSimpUser("joe");
 		TestSimpSession localSession = new TestSimpSession("sess123");
@@ -175,7 +170,6 @@ public class MultiServerUserRegistryTests {
 
 	@Test
 	public void purgeExpiredRegistries() throws Exception {
-
 		// Prepare broadcast message from remote server
 		TestSimpUser testUser = new TestSimpUser("joe");
 		testUser.addSessions(new TestSimpSession("remote-sub"));

spring-orm/src/main/java/org/springframework/orm/hibernate5/support/OpenSessionInViewInterceptor.java

@@ -30,6 +30,7 @@ import org.springframework.orm.hibernate5.SessionFactoryUtils;
 import org.springframework.orm.hibernate5.SessionHolder;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
 import org.springframework.ui.ModelMap;
+import org.springframework.util.Assert;
 import org.springframework.web.context.request.AsyncWebRequestInterceptor;
 import org.springframework.web.context.request.WebRequest;
 import org.springframework.web.context.request.async.CallableProcessingInterceptor;
@@ -79,23 +80,31 @@ public class OpenSessionInViewInterceptor implements AsyncWebRequestInterceptor
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private SessionFactory sessionFactory;
 
 
 	/**
 	 * Set the Hibernate SessionFactory that should be used to create Hibernate Sessions.
 	 */
-	public void setSessionFactory(SessionFactory sessionFactory) {
+	public void setSessionFactory(@Nullable SessionFactory sessionFactory) {
 		this.sessionFactory = sessionFactory;
 	}
 
 	/**
 	 * Return the Hibernate SessionFactory that should be used to create Hibernate Sessions.
 	 */
+	@Nullable
 	public SessionFactory getSessionFactory() {
 		return this.sessionFactory;
 	}
 
+	private SessionFactory obtainSessionFactory() {
+		SessionFactory sf = getSessionFactory();
+		Assert.state(sf != null, "No SessionFactory set");
+		return sf;
+	}
+
 
 	/**
 	 * Open a new Hibernate {@code Session} according and bind it to the thread via the
@@ -112,7 +121,7 @@ public class OpenSessionInViewInterceptor implements AsyncWebRequestInterceptor
 			}
 		}
 
-		if (TransactionSynchronizationManager.hasResource(getSessionFactory())) {
+		if (TransactionSynchronizationManager.hasResource(obtainSessionFactory())) {
 			// Do not modify the Session: just mark the request accordingly.
 			Integer count = (Integer) request.getAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST);
 			int newCount = (count != null ? count + 1 : 1);
@@ -122,10 +131,10 @@ public class OpenSessionInViewInterceptor implements AsyncWebRequestInterceptor
 			logger.debug("Opening Hibernate Session in OpenSessionInViewInterceptor");
 			Session session = openSession();
 			SessionHolder sessionHolder = new SessionHolder(session);
-			TransactionSynchronizationManager.bindResource(getSessionFactory(), sessionHolder);
+			TransactionSynchronizationManager.bindResource(obtainSessionFactory(), sessionHolder);
 
 			AsyncRequestInterceptor asyncRequestInterceptor =
-					new AsyncRequestInterceptor(getSessionFactory(), sessionHolder);
+					new AsyncRequestInterceptor(obtainSessionFactory(), sessionHolder);
 			asyncManager.registerCallableInterceptor(participateAttributeName, asyncRequestInterceptor);
 			asyncManager.registerDeferredResultInterceptor(participateAttributeName, asyncRequestInterceptor);
 		}
@@ -143,7 +152,7 @@ public class OpenSessionInViewInterceptor implements AsyncWebRequestInterceptor
 	public void afterCompletion(WebRequest request, @Nullable Exception ex) throws DataAccessException {
 		if (!decrementParticipateCount(request)) {
 			SessionHolder sessionHolder =
-					(SessionHolder) TransactionSynchronizationManager.unbindResource(getSessionFactory());
+					(SessionHolder) TransactionSynchronizationManager.unbindResource(obtainSessionFactory());
 			logger.debug("Closing Hibernate Session in OpenSessionInViewInterceptor");
 			SessionFactoryUtils.closeSession(sessionHolder.getSession());
 		}
@@ -168,7 +177,7 @@ public class OpenSessionInViewInterceptor implements AsyncWebRequestInterceptor
 	@Override
 	public void afterConcurrentHandlingStarted(WebRequest request) {
 		if (!decrementParticipateCount(request)) {
-			TransactionSynchronizationManager.unbindResource(getSessionFactory());
+			TransactionSynchronizationManager.unbindResource(obtainSessionFactory());
 		}
 	}
 
@@ -183,7 +192,7 @@ public class OpenSessionInViewInterceptor implements AsyncWebRequestInterceptor
 	@SuppressWarnings("deprecation")
 	protected Session openSession() throws DataAccessResourceFailureException {
 		try {
-			Session session = getSessionFactory().openSession();
+			Session session = obtainSessionFactory().openSession();
 			session.setFlushMode(FlushMode.MANUAL);
 			return session;
 		}
@@ -199,7 +208,7 @@ public class OpenSessionInViewInterceptor implements AsyncWebRequestInterceptor
 	 * of the {@code SessionFactory} instance and appends {@link #PARTICIPATE_SUFFIX}.
 	 */
 	protected String getParticipateAttributeName() {
-		return getSessionFactory().toString() + PARTICIPATE_SUFFIX;
+		return obtainSessionFactory().toString() + PARTICIPATE_SUFFIX;
 	}
 
 	private boolean applySessionBindingInterceptor(WebAsyncManager asyncManager, String key) {