public List<String> getSerialPeerIdsBelongsTo(TableName tableName) {
    return peers.values().stream().filter(p -> p.getPeerConfig().isSerial())
      .filter(p -> p.getPeerConfig().needToReplicate(tableName)).map(p -> p.getPeerId())
      .collect(Collectors.toList());
  }
Set a namespace in the peer config means that all tables in this namespace will be replicated
to the peer cluster.
<ol>
<li>If peer config already has a namespace, then not allow set any table of this namespace to
the peer config.</li>
<li>If peer config already has a table, then not allow set this table's namespace to the peer
config.</li>
</ol>
<p>
Set a exclude namespace in the peer config means that all tables in this namespace can't be
replicated to the peer cluster.
<ol>
<li>If peer config already has a exclude namespace, then not allow set any exclude table of
this namespace to the peer config.</li>
<li>If peer config already has a exclude table, then not allow set this table's namespace as a
exclude namespace.</li>
</ol>
hbase-server/src/main/java/org/apache/hadoop/hbase/master/replication/ReplicationPeerManager.java