presto-parser/src/main/java/io/prestosql/sql/tree/ExpressionTreeRewriter.java/ExpressionTreeRewriter/rewriteOrderBy
class ExpressionTreeRewriter:        private OrderBy rewriteOrderBy(OrderBy orderBy, Context<C> context)
        {
            List<SortItem> rewrittenSortItems = rewriteSortItems(orderBy.getSortItems(), context);
            if (sameElements(orderBy.getSortItems(), rewrittenSortItems)) {
                return orderBy;
            }

            return new OrderBy(rewrittenSortItems);
        }