presto-main/src/main/java/io/prestosql/sql/planner/optimizations/OptimizeMixedDistinctAggregations.java/OptimizeMixedDistinctAggregations/getOriginalDistinctAggregateArgs
class OptimizeMixedDistinctAggregations:        public List<Symbol> getOriginalDistinctAggregateArgs()
        {
            return aggregations.values().stream()
                    .filter(aggregation -> aggregation.getMask().isPresent())
                    .flatMap(aggregation -> aggregation.getArguments().stream())
                    .distinct()
                    .map(Symbol::from)
                    .collect(Collectors.toList());
        }