docs: @Override
      public void toJSONString(JSONStringer stringer) throws JSONException {
          super.toJSONString(stringer);
          stringer.key("AGGREGATE_COLUMNS")
                  .array();
          for (int ii = 0; ii < m_aggregateTypes.size(); ii++) {
              stringer.object();
              stringer.keySymbolValuePair(Members.AGGREGATE_TYPE.name(), m_aggregateTypes.get(ii).name());
              stringer.keySymbolValuePair(Members.AGGREGATE_OUTPUT_COLUMN.name(), m_aggregateOutputColumns.get(ii));
              AbstractExpression.toJSONArray(stringer,
                                             Members.AGGREGATE_EXPRESSIONS.name(),
                                             m_aggregateExpressions.get(ii));
              stringer.endObject();
          }
          stringer.endArray();
          AbstractExpression.toJSONArray(stringer,
                                         Members.PARTITIONBY_EXPRESSIONS.name(),
                                         m_partitionByExpressions);
          AbstractExpression.toJSONArrayFromSortList(stringer,
                                                     m_orderByExpressions,
                                                         null);
      }