Polish

The package o.s.messaging.handler.annotation.support was missing
@NonnullApi and @NonNullFields. This commit corrects that and also
adds @Nullable to methods and arguments as needed to address
warnings.

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/AbstractNamedValueMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,7 +26,6 @@ import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
-import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.annotation.ValueConstants;
@@ -61,8 +60,10 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 
 	private final ConversionService conversionService;
 
+	@Nullable
 	private final ConfigurableBeanFactory configurableBeanFactory;
 
+	@Nullable
 	private final BeanExpressionContext expressionContext;
 
 	private final Map<MethodParameter, NamedValueInfo> namedValueInfoCache = new ConcurrentHashMap<>(256);
@@ -70,16 +71,16 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 
 	/**
 	 * Constructor with a {@link ConversionService} and a {@link BeanFactory}.
-	 * @param cs conversion service for converting values to match the
+	 * @param conversionService conversion service for converting values to match the
 	 * target method parameter type
 	 * @param beanFactory a bean factory to use for resolving {@code ${...}} placeholder
 	 * and {@code #{...}} SpEL expressions in default values, or {@code null} if default
 	 * values are not expected to contain expressions
 	 */
-	protected AbstractNamedValueMethodArgumentResolver(ConversionService cs,
+	protected AbstractNamedValueMethodArgumentResolver(ConversionService conversionService,
 			@Nullable ConfigurableBeanFactory beanFactory) {
 
-		this.conversionService = (cs != null ? cs : DefaultConversionService.getSharedInstance());
+		this.conversionService = conversionService;
 		this.configurableBeanFactory = beanFactory;
 		this.expressionContext = (beanFactory != null ? new BeanExpressionContext(beanFactory, null) : null);
 	}
@@ -161,8 +162,9 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 	 * Resolve the given annotation-specified value,
 	 * potentially containing placeholders and expressions.
 	 */
+	@Nullable
 	private Object resolveStringValue(String value) {
-		if (this.configurableBeanFactory == null) {
+		if (this.configurableBeanFactory == null || this.expressionContext == null) {
 			return value;
 		}
 		String placeholdersResolved = this.configurableBeanFactory.resolveEmbeddedValue(value);
@@ -199,6 +201,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 	 * A {@code null} results in a {@code false} value for {@code boolean}s or an
 	 * exception for other primitives.
 	 */
+	@Nullable
 	private Object handleNullValue(String name, @Nullable Object value, Class<?> paramType) {
 		if (value == null) {
 			if (Boolean.TYPE.equals(paramType)) {
@@ -221,7 +224,8 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 	 * @param parameter the argument parameter type
 	 * @param message the message
 	 */
-	protected void handleResolvedValue(Object arg, String name, MethodParameter parameter, Message<?> message) {
+	protected void handleResolvedValue(
+			@Nullable Object arg, String name, MethodParameter parameter, Message<?> message) {
 	}
 
 
@@ -235,9 +239,10 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 
 		private final boolean required;
 
+		@Nullable
 		private final String defaultValue;
 
-		protected NamedValueInfo(String name, boolean required, String defaultValue) {
+		protected NamedValueInfo(String name, boolean required, @Nullable String defaultValue) {
 			this.name = name;
 			this.required = required;
 			this.defaultValue = defaultValue;

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DefaultMessageHandlerMethodFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,11 +26,13 @@ import org.springframework.beans.factory.InitializingBean;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.format.support.DefaultFormattingConversionService;
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.converter.GenericMessageConverter;
 import org.springframework.messaging.converter.MessageConverter;
 import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver;
 import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolverComposite;
 import org.springframework.messaging.handler.invocation.InvocableHandlerMethod;
+import org.springframework.util.Assert;
 import org.springframework.validation.Validator;
 
 /**
@@ -60,15 +62,19 @@ public class DefaultMessageHandlerMethodFactory
 
 	private ConversionService conversionService = new DefaultFormattingConversionService();
 
+	@Nullable
 	private MessageConverter messageConverter;
 
+	@Nullable
 	private Validator validator;
 
+	@Nullable
 	private List<HandlerMethodArgumentResolver> customArgumentResolvers;
 
 	private final HandlerMethodArgumentResolverComposite argumentResolvers =
 			new HandlerMethodArgumentResolverComposite();
 
+	@Nullable
 	private BeanFactory beanFactory;
 
 
@@ -114,6 +120,7 @@ public class DefaultMessageHandlerMethodFactory
 	 * the ones configured by default. This is an advanced option. For most use cases
 	 * it should be sufficient to use {@link #setCustomArgumentResolvers(java.util.List)}.
 	 */
+	@SuppressWarnings("ConstantConditions")
 	public void setArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
 		if (argumentResolvers == null) {
 			this.argumentResolvers.clear();
@@ -151,11 +158,11 @@ public class DefaultMessageHandlerMethodFactory
 
 	protected List<HandlerMethodArgumentResolver> initArgumentResolvers() {
 		List<HandlerMethodArgumentResolver> resolvers = new ArrayList<>();
-		ConfigurableBeanFactory cbf = (this.beanFactory instanceof ConfigurableBeanFactory ?
+		ConfigurableBeanFactory beanFactory = (this.beanFactory instanceof ConfigurableBeanFactory ?
 				(ConfigurableBeanFactory) this.beanFactory : null);
 
 		// Annotation-based argument resolution
-		resolvers.add(new HeaderMethodArgumentResolver(this.conversionService, cbf));
+		resolvers.add(new HeaderMethodArgumentResolver(this.conversionService, beanFactory));
 		resolvers.add(new HeadersMethodArgumentResolver());
 
 		// Type-based argument resolution
@@ -164,6 +171,8 @@ public class DefaultMessageHandlerMethodFactory
 		if (this.customArgumentResolvers != null) {
 			resolvers.addAll(this.customArgumentResolvers);
 		}
+
+		Assert.notNull(this.messageConverter, "MessageConverter not configured");
 		resolvers.add(new PayloadArgumentResolver(this.messageConverter, this.validator));
 
 		return resolvers;

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,8 +43,8 @@ public class DestinationVariableMethodArgumentResolver extends AbstractNamedValu
 			DestinationVariableMethodArgumentResolver.class.getSimpleName() + ".templateVariables";
 
 
-	public DestinationVariableMethodArgumentResolver(ConversionService cs) {
-		super(cs, null);
+	public DestinationVariableMethodArgumentResolver(ConversionService conversionService) {
+		super(conversionService, null);
 	}
 
 

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,8 +43,10 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 	private static final Log logger = LogFactory.getLog(HeaderMethodArgumentResolver.class);
 
 
-	public HeaderMethodArgumentResolver(ConversionService cs, ConfigurableBeanFactory beanFactory) {
-		super(cs, beanFactory);
+	public HeaderMethodArgumentResolver(
+			ConversionService conversionService, @Nullable ConfigurableBeanFactory beanFactory) {
+
+		super(conversionService, beanFactory);
 	}
 
 
@@ -94,9 +96,9 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 	}
 
 	@SuppressWarnings("unchecked")
+	@Nullable
 	private Map<String, List<String>> getNativeHeaders(Message<?> message) {
-		return (Map<String, List<String>>) message.getHeaders().get(
-				NativeMessageHeaderAccessor.NATIVE_HEADERS);
+		return (Map<String, List<String>>) message.getHeaders().get(NativeMessageHeaderAccessor.NATIVE_HEADERS);
 	}
 
 	@Override

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,6 +43,7 @@ import org.springframework.util.StringUtils;
  */
 public class MessageMethodArgumentResolver implements HandlerMethodArgumentResolver {
 
+	@Nullable
 	private final MessageConverter converter;
 
 

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/PayloadArgumentResolver.java

@@ -55,6 +55,7 @@ public class PayloadArgumentResolver implements HandlerMethodArgumentResolver {
 
 	private final MessageConverter converter;
 
+	@Nullable
 	private final Validator validator;
 
 	private final boolean useDefaultResolution;
@@ -76,7 +77,7 @@ public class PayloadArgumentResolver implements HandlerMethodArgumentResolver {
 	 * @param messageConverter the MessageConverter to use (required)
 	 * @param validator the Validator to use (optional)
 	 */
-	public PayloadArgumentResolver(MessageConverter messageConverter, Validator validator) {
+	public PayloadArgumentResolver(MessageConverter messageConverter, @Nullable Validator validator) {
 		this(messageConverter, validator, true);
 	}
 
@@ -89,7 +90,7 @@ public class PayloadArgumentResolver implements HandlerMethodArgumentResolver {
 	 * all parameters; if "false" then only arguments with the {@code @Payload}
 	 * annotation are supported.
 	 */
-	public PayloadArgumentResolver(MessageConverter messageConverter, Validator validator,
+	public PayloadArgumentResolver(MessageConverter messageConverter, @Nullable Validator validator,
 			boolean useDefaultResolution) {
 
 		Assert.notNull(messageConverter, "MessageConverter must not be null");

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/package-info.java

@@ -1,4 +1,9 @@
 /**
  * Support classes for working with annotated message-handling methods.
  */
+@NonNullApi
+@NonNullFields
 package org.springframework.messaging.handler.annotation.support;
+
+import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;