cluster-metrics/src/main/protobuf/ClusterMetricsMessages.proto
cluster-tools/src/main/protobuf/ClusterClientMessages.proto

cluster-metrics/src/main/protobuf/ClusterMetricsMessages.proto
cluster-tools/src/main/protobuf/DistributedPubSubMessages.proto

cluster-metrics/src/main/scala/org/apache/pekko/cluster/metrics/protobuf/MessageSerializer.scala
cluster-tools/src/main/scala/org/apache/pekko/cluster/pubsub/protobuf/DistributedPubSubMessageSerializer.scala