code: public static void sendClose(final int code, String reason, final WebSocketChannel wsChannel, final WebSocketCallback<Void> callback) {
          sendClose(new CloseMessage(code, reason), wsChannel, callback);
      }
docs: Sends a complete close message, invoking the callback when complete
  
  @param code The close code
  @param wsChannel The web socket channel
  @param callback The callback to invoke on completion