code: public SortField[] sortFields() {
          return new SortField[]{new SortField(FIELD_NAME, new FieldComparatorSource() {
              @Override
              public FieldComparator<?> newComparator(String field,
                                                      int hits,
                                                      int sort,
                                                      boolean reversed) throws IOException {
                  return new ClusteringKeySorter(ClusteringKeyMapper.this, hits, field);
              }
          })};
      }
docs: Returns a Lucene {@link SortField} array for sorting documents/rows according to the column family name.
  
  @return A Lucene {@link SortField} array for sorting documents/rows according to the column family name.