presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/SingleDistinctAggregationToGroupBy.java/SingleDistinctAggregationToGroupBy/removeDistinct
class SingleDistinctAggregationToGroupBy:    private static Aggregation removeDistinct(Aggregation aggregation)
    {
        checkArgument(aggregation.isDistinct(), "Expected aggregation to have DISTINCT input");

        return new Aggregation(
                aggregation.getResolvedFunction(),
                aggregation.getArguments(),
                false,
                aggregation.getFilter(),
                aggregation.getOrderingScheme(),
                aggregation.getMask());
    }