Right now in consumer / producer, the default client-id is set as consumer-[suffix] and producer-[suffix] which is not very meaningful; on the other hand, since client-ids will be shown on the broker request logs it can be very useful for debugging purposes.
So I'd propose we change their default values as the following:
1. For producer:
producer-[transactionalId]-[suffix] where transactionalId would be set to none if null.
2. For consumer:
consumer-[groupId]-[instanceId or suffix] where groupId would be set to none if null, and suffix would only be used if instanceId is set to null.