presto-main/src/main/java/io/prestosql/operator/HashSemiJoinOperator.java/HashSemiJoinOperator/create
class HashSemiJoinOperator:        @Override
        public WorkProcessorOperator create(ProcessorContext processorContext, WorkProcessor<Page> sourcePages)
        {
            return new HashSemiJoinOperator(Optional.of(sourcePages), setSupplier, probeJoinChannel, probeJoinHashChannel, processorContext.getMemoryTrackingContext());
        }