default void peerSyncReplicationStateChange(String peerId, SyncReplicationState from,
    SyncReplicationState to, int stage) {
  }
Get notification for replication peer events. Mainly used for telling the {@code WALProvider} to
close some remote WAL if not used any more.
hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/PeerActionListener.java