Sonar Fixes

Critical smells for packages `o.s.i.i*`.

* Polishing

* Polishing

* Missed saving a file.

* Polishing - PR Comments

* More PR comments.

spring-integration-core/src/main/java/org/springframework/integration/handler/support/PayloadsArgumentResolver.java

@@ -62,8 +62,8 @@ public class PayloadsArgumentResolver extends AbstractExpressionEvaluator
 		Collection<Message<?>> messages = (Collection<Message<?>>) payload;
 
 		if (!this.expressionCache.containsKey(parameter)) {
-			Payloads payloads = parameter.getParameterAnnotation(Payloads.class); // NOSONAR never null - supportsParameter()
-			String expression = payloads.value();
+			Payloads payloads = parameter.getParameterAnnotation(Payloads.class);
+			String expression = payloads.value(); // NOSONAR never null - supportsParameter()
 			if (StringUtils.hasText(expression)) {
 				this.expressionCache.put(parameter, EXPRESSION_PARSER.parseExpression("![payload." + expression + "]"));
 			}

spring-integration-core/src/main/java/org/springframework/integration/mapping/OutboundMessageMapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -16,16 +16,19 @@
 
 package org.springframework.integration.mapping;
 
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**
  * Strategy interface for mapping from a {@link Message} to an Object.
  *
  * @author Mark Fisher
+ * @author Gary Russell
  */
 @FunctionalInterface
 public interface OutboundMessageMapper<T> {
 
+	@Nullable
 	T fromMessage(Message<?> message) throws Exception;
 
 }