https://pekko.apache.org/japi/pekko/snapshot/org/apache/pekko/cluster/pubsub/DistributedPubSubMediator.UnsubscribeAck.html
DistributedPubSubMediator.UnsubscribeAck
declaration: package: org.apache.pekko.cluster.pubsub, class: DistributedPubSubMediator, class: UnsubscribeAck