void broadcastToOtherPartitions(ControlMessage message, SystemStreamPartition ssp, MessageCollector collector) {
    SystemStream systemStream = ssp.getSystemStream();
    int partitionCount = getPartitionCount(systemStream);
    int currentPartition = ssp.getPartition().getPartitionId();
    for (int i = 0; i < partitionCount; i++) {
      if (i != currentPartition) {
        LOG.debug(String.format("Broadcast %s message from task %s to %s partition %d for aggregation",
            MessageType.of(message).name(), message.getTaskName(), systemStream, i));
        OutgoingMessageEnvelope envelopeOut = new OutgoingMessageEnvelope(systemStream, i, null, message);
        collector.send(envelopeOut);
      }
    }
  }
This is a helper class to send control messages to an intermediate stream
samza-core/src/main/java/org/apache/samza/operators/impl/ControlMessageSender.java