presto-main/src/main/java/io/prestosql/operator/HashAggregationOperator.java/HashAggregationOperator/duplicate
class HashAggregationOperator:        @Override
        public OperatorFactory duplicate()
        {
            return new HashAggregationOperatorFactory(
                    operatorId,
                    planNodeId,
                    groupByTypes,
                    groupByChannels,
                    globalAggregationGroupIds,
                    step,
                    produceDefaultOutput,
                    accumulatorFactories,
                    hashChannel,
                    groupIdChannel,
                    expectedGroups,
                    maxPartialMemory,
                    spillEnabled,
                    memoryLimitForMerge,
                    memoryLimitForMergeWithMemory,
                    spillerFactory,
                    joinCompiler,
                    useSystemMemory);
        }