code: @POST
      public void broadcast(String message) {
          AtmosphereResource r = (AtmosphereResource) request.getAttribute(ApplicationConfig.ATMOSPHERE_RESOURCE);
  
          if (r != null) {
              r.getBroadcaster().broadcast(message);
          } else {
              throw new IllegalStateException();
          }
      }
docs: Echo the chat message. Jackson can clearly be used here, but for simplicity we just echo what we receive.
  
  @param message