INT-3665: Remove Deprecations and Resolve Issues

https://jira.spring.io/browse/INT-3665

Fixes according Travis report

Introduce `...ExpressionString(String)` setter

Some further fixes and polishing

Address PR comments

spring-integration-xml/src/main/java/org/springframework/integration/xml/AggregatedXmlMessageValidationException.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.
@@ -17,7 +17,6 @@
 package org.springframework.integration.xml;
 
 import java.util.Collections;
-import java.util.Iterator;
 import java.util.List;
 
 /**
@@ -44,15 +43,6 @@ public class AggregatedXmlMessageValidationException extends RuntimeException {
 		return message.toString();
 	}
 
-	/**
-	 * @return The exception iterator.
-	 * @deprecated in favor of #getExceptions
-	 */
-	@Deprecated
-	public Iterator<Throwable> exceptionIterator() {
-		return exceptions.iterator();
-	}
-
 	public List<Throwable> getExceptions() {
 		return Collections.unmodifiableList(exceptions);
 	}