default void postTransitReplicationPeerSyncReplicationState(
    final ObserverContext<MasterCoprocessorEnvironment> ctx, String peerId,
    SyncReplicationState from, SyncReplicationState to) throws IOException {
  }
Called after transit current cluster state for the specified synchronous replication peer
@param ctx    the environment to interact with the framework and master
@param peerId a short name that identifies the peer
@param from   the old state
@param to     the new state
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterObserver.java