title: Spring Stomp @SubscribeMapping for User Destination
body: <p>I am trying to get notified when an user subscribes to a stomp user destination using @SubscribeMapping annotation. My ideia is to send some initialization data to when it  joins.</p>
  
  <p>Although i am not being able to get this working:</p>
  
  <p>Javascript:</p>
  
  <pre><code>stompClient.subscribe('/user/monitor', function(msg) {
              console.log(msg);    
          });
  </code></pre>
  
  <p>Java side:</p>
  
  <pre><code>@SubscribeMapping("/monitor-user{clientId}")
  public void init(@DestinationVariable("clientId") String clientId) {
      messagingTemplate.convertAndSend("/user/" + clientId + "/monitor", getOps());
  }
  </code></pre>
  
  <p>I tried many mapping combinations such as "/user/monitor-{clientId}", "/user/monitor" (Removing clientId), no success at all.</p>
  
  <p>What is the expected mapping value so this get called?</p>
  
  <p>Thank you!</p>