MessagingException provides null description (instead of empty String) to NestedRuntimeException

Issue: SPR-13447

spring-messaging/src/main/java/org/springframework/messaging/MessagingException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -32,7 +32,7 @@ public class MessagingException extends NestedRuntimeException {
 
 
 	public MessagingException(Message<?> message) {
-		super("");
+		super(null);
 		this.failedMessage = message;
 	}
 
@@ -52,7 +52,7 @@ public class MessagingException extends NestedRuntimeException {
 	}
 
 	public MessagingException(Message<?> message, Throwable cause) {
-		super("", cause);
+		super(null, cause);
 		this.failedMessage = message;
 	}