Currently, during the Kafka upgrade, when inter.broker.protocol.version and log.message.format.version are not set, we update them both together (after all Kafka brokers are rolled to the new Kafka version). This is sub-optimal and we should first update the inter.broker.protocol.version and only afterwards in a separate roll update log.message.format.version.
The documentation has been done already in https://issues.redhat.com/browse/ENTMQST-2783.