code: @Override
      public void onMessage(StreamMessage received)
      {
          if (this.reloadConfig && this.watcher != null)
          {
              Map<String, Object> reloadedConfig = null;
  
              try
              {
                  reloadedConfig = this.watcher.readIfUpdated();
              }
              catch (IOException ex)
              {
                  String logFormat = "Config file reload failed. Skip reload config.";
                  logger.warn(logFormat, ex);
              }
  
              if (reloadedConfig != null)
              {
                  onUpdate(reloadedConfig);
              }
          }
  
          this.executingKeyHistory = received.getHeader().getHistory();
          this.responsed = false;
  
          // Execute message processing.
          // This class not handles exceptions.
          // Because if throws exception, this class not need ack.
          try
          {
              onExecute(received);
          }
          finally
          {
              clearExecuteStatus();
          }
  
          // If not responsed, auto ack
          if (this.responsed == false)
          {
              super.ack();
          }
      }
docs: Execute when receive message.
  
  @param received received message