private void returnSelf() {
    if (originalTimeout != -1) {
      recoverTimeout();
    }
    clientManager.returnClient(endpoint, this);
  }
return self, the method doesn't need to be called by the user and will be triggered after the
RPC is finished.
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/client/async/AsyncDataNodeInternalServiceClient.java