public void trackHandler(final PipeTransferTrackableHandler handler) {
    pendingHandlers.put(handler, handler);
  }
Add failure {@link EnrichedEvent}s to retry queue.

@param events {@link EnrichedEvent}s to retry
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/protocol/thrift/async/IoTDBDataRegionAsyncConnector.java