@Override
  public String toString() {
    return tablename + "/" + Bytes.toString(encodedRegionName) + "/" + sequenceId;
  }
@return the cluster id on which the change has originated. It there is no such cluster, it
        returns DEFAULT_CLUSTER_ID (cases where replication is not enabled)
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/WALKeyImpl.java