title: Response body null when call succeeded (android)
body: <p>Please help. I invoke method on server from android and i got success with null response body. My server is ASP.NET Web API, on android client I use retrofit2.</p>
  
  <p>Method on the server (route is "Players/IsParticipant/"):</p>
  
  <pre><code>        [AllowAnonymous]
      [Route("IsParticipant"), HttpGet]
      public IHttpActionResult IsParticipant(int meetingId, string username)
      {
          return Ok(true);
      }
  </code></pre>
  
  <p>And in android:</p>
  
  <pre><code>@GET("players/isParticipant")
  Call&lt;Boolean&gt; isParticipant(@Query("username") String username, @Query("meetingId") int meetingId);
  </code></pre>
  
  <p>When I invoke it:</p>
  
  <pre><code>Call&lt;Boolean&gt; call = service.isParticipant("aa", 1);
      call.enqueue(new CustomCallback&lt;Boolean&gt;(this)
      {
  
          @Override
          public void onSuccess(Boolean model)
          {
              DialogUtils.Show(getApplicationContext(), model.toString());
          }
      });
  </code></pre>
  
  <p>I got an error because model is null. Why? How am I supposed to fix it? I would be grateful for any advice.</p>