public int getMessageNumber() {
      return msgNum;
    }
@param chunkStream the data to send back, if null then all the following parameters are
       ignored and any future replies from this member will be ignored, and the streaming of
       chunks is considered aborted by the receiver.

@param msgNum message number in this series (0-based)
@param lastMsg if this is the last message in this series
geode-core/src/main/java/org/apache/geode/distributed/internal/streaming/StreamingOperation.java