presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/SetOperationNodeTranslator.java/SetOperationNodeTranslator/TranslationResult
class SetOperationNodeTranslator:        public TranslationResult(PlanNode planNode, List<Expression> presentExpressions)
        {
            this.planNode = requireNonNull(planNode, "AggregationNode is null");
            this.presentExpressions = ImmutableList.copyOf(requireNonNull(presentExpressions, "AggregationOutputs is null"));
        }