TopicDurability
class TopicDurability @InternalWowApi constructor(val replicationFactor: Int, val minInsyncReplicas: Int)
What a write to a topic survives: its partitions' fewest replicas (replicationFactor) and the replicas an acks=all write waits for (minInsyncReplicas, the broker's 1 when the topic sets none). A command accepted on a topic is durable once acknowledged only when both are at least 2: then losing one broker loses no acknowledged write.