presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/AddExchangesBelowPartialAggregationOverGroupIdRuleSet.java/AddExchangesBelowExchangePartialAggregationGroupId/getPattern
class AddExchangesBelowExchangePartialAggregationGroupId:        @Override
        public Pattern<ExchangeNode> getPattern()
        {
            return WITHOUT_PROJECTION;
        }