docs: public boolean isOutputOrdered (List<AbstractExpression> sortExpressions, List<SortDirectionType> sortDirections) {
          assert(sortExpressions.size() == sortDirections.size());
          if (m_children.size() == 1) {
              return m_children.get(0).isOutputOrdered(sortExpressions, sortDirections);
          }
          return false;
      }