@Override
        public RelNode visit(SortQueryOperation sort) {
            List<RexNode> rexNodes = convertToRexNodes(sort.getOrder());
            return relBuilder.sortLimit(sort.getOffset(), sort.getFetch(), rexNodes)
                    .build();
        }
Get the {@link AggCall} correspond to the aggregate or table aggregate expression.
core/src/main/java/org/apache/flink/table/planner/plan/QueryOperationConverter.java