title: Not able to set header to AMQP Message using MessageProperties
body: <p>The below code shows how I am setting header and message type to AMQP message.</p>
  
  <pre><code>MessageProperties properties = new MessageProperties();
      properties.setHeader("KEY", "HOUSE");
      properties.setContentType(MessageProperties.CONTENT_TYPE_JSON);
  Message message = new Message("1234567;Branch A;SALES;3000.50;Pending approval".getBytes(), properties);
  rabbitTemplate.sendAndReceive("", QUEUE_NAME, message);
  </code></pre>
  
  <p>After sending the message in the queue, the message is received by Transformer.</p>
  
  <pre><code>@Transformer(inputChannel = "inboundChannel", outputChannel = "toutboundChannel")
  public Property buildProperty(Message&lt;String&gt; property){
      LOGGER.info("message received :: HEADERS: {}, PAYLOAD :{}", property.getHeaders(), property.getPayload());
  ....
  }    
  </code></pre>
  
  <p>In the logs, the header "KEY: HOUSE" is missing and even the message type is not JSON and "text/plain" instead.</p>
  
  <pre><code>LOGS:
  [SimpleAsyncTaskExecutor-1] INFO com.demo.maven.spring.integration.endpoint.TransformerRequestBuilder - message received :: HEADERS: {amqp_receivedRoutingKey=mobile.queue, amqp_deliveryTag=2, amqp_replyTo=amq.rabbitmq.reply-to.g2dkABByYWJiaXRAbG9jYWxob3N0AAAW9QAAAAAD.tTIFOS2gsM7qIlGYaybfrg==, amqp_deliveryMode=PERSISTENT, amqp_redelivered=true, id=399dda4f-4ba1-7cf4-2310-03dbfbac82b6, contentType=text/plain, timestamp=1421649922840}, PAYLOAD :1234567;Branch A;SALES;3000.50;Pending approval
  </code></pre>