Kafka Consumer Rebalance protocol: generation id

The latest Kafka client (KafkaConsumer) is able to obtain a generation id from the metadata. I see that generation id is autoincremented on each rebalance, and each consumer in the consumer group receives the same generation id after the same rebalance.

Need help with the documentation: I’ve found a document that describes the generation id but its state is Under Discussion.
Does anybody know the document describing Kafka Consumer Rebalance protocol generation id in the Accepted state?