presto-main/src/main/java/io/prestosql/operator/TopNOperator.java/TopNOperator/create
class TopNOperator:        @Override
        public AdapterWorkProcessorOperator create(ProcessorContext processorContext)
        {
            return new TopNOperator(
                    processorContext.getMemoryTrackingContext(),
                    Optional.empty(),
                    sourceTypes,
                    n,
                    sortChannels,
                    sortOrders);
        }