presto-main/src/main/java/io/prestosql/operator/StreamingAggregationOperator.java/StreamingAggregationOperator/StreamingAggregationOperatorFactory
class StreamingAggregationOperator:        public StreamingAggregationOperatorFactory(int operatorId, PlanNodeId planNodeId, List<Type> sourceTypes, List<Type> groupByTypes, List<Integer> groupByChannels, Step step, List<AccumulatorFactory> accumulatorFactories, JoinCompiler joinCompiler)
        {
            this.operatorId = operatorId;
            this.planNodeId = requireNonNull(planNodeId, "planNodeId is null");
            this.sourceTypes = ImmutableList.copyOf(requireNonNull(sourceTypes, "sourceTypes is null"));
            this.groupByTypes = ImmutableList.copyOf(requireNonNull(groupByTypes, "groupByTypes is null"));
            this.groupByChannels = ImmutableList.copyOf(requireNonNull(groupByChannels, "groupByChannels is null"));
            this.step = step;
            this.accumulatorFactories = ImmutableList.copyOf(requireNonNull(accumulatorFactories, "accumulatorFactories is null"));
            this.joinCompiler = requireNonNull(joinCompiler, "joinCompiler is null");
        }