default void preAddReplicationPeer(final ObserverContext<MasterCoprocessorEnvironment> ctx,
    String peerId, ReplicationPeerConfig peerConfig) throws IOException {
  }
Called before add a replication peer
@param ctx        the environment to interact with the framework and master
@param peerId     a short name that identifies the peer
@param peerConfig configuration for the replication peer
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterObserver.java