private void migrateQueues(ZKReplicationQueueStorageForMigration oldQueueStorage)
    throws Exception {
    MigrationIterator<Pair<ServerName, List<ZkReplicationQueueData>>> iter =
      oldQueueStorage.listAllQueues();
    for (;;) {
      Pair<ServerName, List<ZkReplicationQueueData>> pair = iter.next();
      if (pair == null) {
        return;
      }
      queueStorage.batchUpdateQueues(pair.getFirst(),
        pair.getSecond().stream().filter(data -> peers.containsKey(data.getQueueId().getPeerId()))
          .map(this::convert).collect(Collectors.toList()));
    }
  }
For replication peer cluster key or endpoint class, null and empty string is same. So here
don't use {@link StringUtils#equals(CharSequence, CharSequence)} directly.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/replication/ReplicationPeerManager.java