docs: private boolean beat(RemotingClientDelegate remotingClient, String addr) {
  
          HeartBeatRequest commandBody = appContext.getCommandBodyWrapper().wrapper(new HeartBeatRequest());
  
          RemotingCommand request = RemotingCommand.createRequestCommand(
                  JobProtos.RequestCode.HEART_BEAT.code(), commandBody);
          try {
              RemotingCommand response = remotingClient.getRemotingClient().invokeSync(addr, request, 5000);
              if (response != null && JobProtos.ResponseCode.HEART_BEAT_SUCCESS ==
                      JobProtos.ResponseCode.valueOf(response.getCode())) {
                  if (LOGGER.isDebugEnabled()) {
                      LOGGER.debug("heart beat success. ");
                  }
                  return true;
              }
          } catch (Exception e) {
              LOGGER.warn(e.getMessage());
          }
          return false;
      }