Lazy resolution of the JMS message

Previously, any `javax.jms.Message` was converted eagerly to the Message
abstraction. This leads to unnecessary conversion if the Payload is not
requested by the underlying method (i.e. if the `javax.jms.Message` is
injected directly).

This commit returns a `Message` implementation that holds the
`javax.jms.Message` and lazily resolve the payload or the headers on
demand (that is the first time they are requested).

Issue: SPR-13777

spring-jms/src/main/java/org/springframework/jms/support/converter/MessagingMessageConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -16,7 +16,6 @@
 
 package org.springframework.jms.support.converter;
 
-import java.util.Map;
 import javax.jms.JMSException;
 import javax.jms.Session;
 
@@ -24,7 +23,7 @@ import org.springframework.beans.factory.InitializingBean;
 import org.springframework.jms.support.JmsHeaderMapper;
 import org.springframework.jms.support.SimpleJmsHeaderMapper;
 import org.springframework.messaging.Message;
-import org.springframework.messaging.support.MessageBuilder;
+import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.Assert;
 
 /**
@@ -104,12 +103,7 @@ public class MessagingMessageConverter implements MessageConverter, Initializing
 		if (message == null) {
 			return null;
 		}
-		Map<String, Object> mappedHeaders = this.headerMapper.toHeaders(message);
-		Object convertedObject = extractPayload(message);
-		MessageBuilder<Object> builder = (convertedObject instanceof org.springframework.messaging.Message) ?
-				MessageBuilder.fromMessage((org.springframework.messaging.Message<Object>) convertedObject) :
-				MessageBuilder.withPayload(convertedObject);
-		return builder.copyHeadersIfAbsent(mappedHeaders).build();
+		return new LazyResolutionMessage(message);
 	}
 
 	/**
@@ -127,4 +121,44 @@ public class MessagingMessageConverter implements MessageConverter, Initializing
 		return this.payloadConverter.toMessage(payload, session);
 	}
 
+	private MessageHeaders extractHeaders(javax.jms.Message message) {
+		return this.headerMapper.toHeaders(message);
+	}
+
+
+	private class LazyResolutionMessage implements Message<Object> {
+
+		private final javax.jms.Message message;
+
+		private Object payload;
+
+		private MessageHeaders headers;
+
+		public LazyResolutionMessage(javax.jms.Message message) {
+			this.message = message;
+		}
+
+		@Override
+		public Object getPayload() {
+			if (this.payload == null) {
+				try {
+					this.payload = extractPayload(this.message);
+				}
+				catch (JMSException ex) {
+					throw new MessageConversionException(
+							"Failed to extract payload from [" + this.message + "]", ex);
+				}
+			}
+			return this.payload;
+		}
+
+		@Override
+		public MessageHeaders getHeaders() {
+			if (this.headers == null) {
+				this.headers = extractHeaders(this.message);
+			}
+			return this.headers;
+		}
+	}
+
 }