@Override
  public void transfer(Event event) throws Exception {
    asyncTransferQueuedEventsIfNecessary();
    transferBatchedEventsIfNecessary();

    // Transfer deletion
    if (event instanceof PipeDeleteDataNodeEvent) {
      final PipeDeleteDataNodeEvent deleteDataNodeEvent = (PipeDeleteDataNodeEvent) event;
      final boolean enqueueResult = addEvent2Buffer(deleteDataNodeEvent);
      if (!enqueueResult) {
        throw new PipeRuntimeConnectorRetryTimesConfigurableException(
            ENQUEUE_EXCEPTION_MSG, Integer.MAX_VALUE);
      }

      transferDeletion(deleteDataNodeEvent);
      return;
    }

    if (!(event instanceof PipeHeartbeatEvent)) {
      LOGGER.warn(
          "PipeConsensusAsyncConnector does not support transferring generic event: {}.", event);
    }
  }
PipeConsensus only need transfer heartbeat event here. And heartbeat event doesn't need to be
added to transferBuffer.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/protocol/pipeconsensus/PipeConsensusAsyncConnector.java