private Map<TableName, List<String>>
    unmodifiableTableCFsMap(Map<TableName, List<String>> tableCFsMap) {
    Map<TableName, List<String>> newTableCFsMap = new HashMap<>();
    tableCFsMap.forEach((table, cfs) -> newTableCFsMap.put(table,
      cfs != null ? Collections.unmodifiableList(cfs) : null));
    return Collections.unmodifiableMap(newTableCFsMap);
  }
A configuration for the replication peer cluster.
hbase-client/src/main/java/org/apache/hadoop/hbase/replication/ReplicationPeerConfig.java