question: public void send ( CoordinatorStreamMessage message ) { log . debug ( "Sending {}" , message ) ; try { String source = message . getSource ( ) ; byte [ ] key = keySerde . toBytes ( Arrays . asList ( message . getKeyArray ( ) ) ) ; byte [ ] value = null ; if ( ! message . isDelete ( ) ) { value = messageSerde . toBytes ( message . getMessageMap ( ) ) ; } OutgoingMessageEnvelope envelope = new OutgoingMessageEnvelope ( systemStream , Integer . valueOf ( 0 ) , key , value ) ; systemProducer . send ( source , envelope ) ; } catch ( Exception e ) { throw new SamzaException ( e ) ; } }
target:  Serialize and send a coordinator stream message.