@Override
  public SubscriptionPollPayload deserialize(final ByteBuffer buffer) {
    this.fileName = ReadWriteIOUtils.readString(buffer);
    this.nextWritingOffset = ReadWriteIOUtils.readLong(buffer);
    final int size = ReadWriteIOUtils.readInt(buffer);
    this.filePiece = ReadWriteIOUtils.readBytes(buffer, size);
    return this;
  }
The piece of the file content.
iotdb-client/service-rpc/src/main/java/org/apache/iotdb/rpc/subscription/payload/poll/FilePiecePayload.java