@Explain(displayName = "sort columns", explainLevels = { Level.USER, Level.DEFAULT, Level.EXTENDED })
  public List<String> getSortColumnsExplain() {
    return sortColumns.stream()
        .map(t -> t.getCol() + " " + DirectionUtils.codeToText(t.getOrder()))
        .collect(Collectors.toList());
  }
DDL task description for ALTER TABLE ... CLUSTERED BY ... SORTED BY ... [INTO ... BUCKETS] commands.
ql/src/java/org/apache/hadoop/hive/ql/ddl/table/storage/cluster/AlterTableClusteredByDesc.java