title: RequestFactory: error.getExceptionType() returns null in Receiver#onFailure
body: <p>In the server side i have:</p>
  
  <pre><code>public void throwException() throws Exception {
          throw new NullPointerException("fslkdjflks");
  }
  </code></pre>
  
  <p>in the client side i have:</p>
  
  <pre><code>_requestFactory.myService().throwException().fire(new Receiver&lt;Void&gt;() {
  
              @Override
              public void onSuccess(Void response) {
                  // TODO Auto-generated method stub
  
              }
  
              @Override
              public void onFailure(ServerFailure error) {
                  // TODO Auto-generated method stub
                  Window.alert(error.getExceptionType() + " " + error.getMessage());
  
              }
  
          });
  </code></pre>
  
  <p>error.getExceptionType() returns null and not the type of the exception. Any idea why?</p>
  
  <p>Thanks,
  Gilad.</p>