Motivation

The motivation of for moving to a new set of consumer client APIs with broker side co-ordination is laid out here.

...

{
  CorrelationId          => int32
  GroupId                => String
  ConsumerId             => String
  ErrorCode              => int16
}

With wildcard subscription (for example, whitelist and blacklist), the consumers are responsible to discover matching topics through topic metadata request. That is, its topic metadata request will contain an empty topic list, whose response then will return the partition info of all topics, it will then filter the topics that match its wildcard expression, and then updates the subscription list. Again, if the subscription list has changed from the previous values, it will start the consumer re-join group procedure.

...