@Override
  protected PeerSyncReplicationStateTransitionState getInitialState() {
    return PeerSyncReplicationStateTransitionState.PRE_PEER_SYNC_REPLICATION_STATE_TRANSITION;
  }
The procedure for transit current sync replication state for a synchronous replication peer.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/replication/TransitPeerSyncReplicationStateProcedure.java