code: @Handler
      public void onResponse(Response event, WebAppMsgChannel appChannel)
              throws InterruptedException {
          appChannel.handleResponse(event);
      }
docs: Handles a response event from downstream by sending it through an
  {@link HttpResponseEncoder} that generates the data (encoded information)
  and sends it upstream with {@link Output} events. Depending on whether
  the response has a body, subsequent {@link Output} events can
  follow.
  
  @param event
  the response event
  @throws InterruptedException if the execution was interrupted