@Override
    public List<Integer> getIndexes() {
      return indexes;
    }
SortCol.

An implementation of BucketSortCol which contains known aliases/indexes of equivalent columns
which data is determined to be sorted on.  Unlike aliases, and indexes the sort order is known
to be constant for all equivalent columns.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/BucketingSortingCtx.java