@Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((key == null) ? 0 : key.hashCode());
    result = prime * result + ((message == null) ? 0 : message.hashCode());
    result = prime * result + ((offset == null) ? 0 : offset.hashCode());
    result = prime * result + ((systemStreamPartition == null) ? 0 : systemStreamPartition.hashCode());
    return result;
  }
This method is deprecated in favor of WatermarkManager.buildEndOfStreamEnvelope(SystemStreamPartition ssp).

@param ssp The SSP that is at end-of-stream.
@return an IncomingMessageEnvelope corresponding to end-of-stream for that SSP.
samza-api/src/main/java/org/apache/samza/system/IncomingMessageEnvelope.java