title: Custom Stomp Headers using Spring websockets
body: <p>I have a basic spring websocket application which currently sends basic data to subscribers.
  Currently the system uses the <code>SimpMessageSendingOperations</code> class as the message handler.
  If I call <code>SimpMessageSendingOperations.convertAndSend(destination, object)</code> then the object is converted and received by the subscribed clients.</p>
  
  <p>I would like to be able to send a custom header to the clients.
  I have tried using the <code>SimpMessageSendingOperations.convertAndSend(destination, object, headers)</code> method to do this.  However the custom header is not included in the stomp message.</p>
  
  <p>Debugging through the code it looks like <code>StompHeaderAccessor.toStompHeaderMap()</code> method calls 
  <code>toNativeHeaderMap()</code> which uses the native header and the original native header maps to build up the stomp headers.</p>
  
  <p>Is there a way to get a custom header added to stomp message?</p>