presto-main/src/main/java/io/prestosql/operator/TaskOutputOperator.java/TaskOutputOperator/createOutputOperator
class TaskOutputOperator:        @Override
        public OperatorFactory createOutputOperator(int operatorId, PlanNodeId planNodeId, List<Type> types, Function<Page, Page> pagePreprocessor, PagesSerdeFactory serdeFactory)
        {
            return new TaskOutputOperatorFactory(operatorId, planNodeId, outputBuffer, pagePreprocessor, serdeFactory);
        }