presto-main/src/main/java/io/prestosql/operator/HashSemiJoinOperator.java/HashSemiJoinOperator/createOperator
class HashSemiJoinOperator:        @Override
        public Operator createOperator(DriverContext driverContext)
        {
            checkState(!closed, "Factory is already closed");
            OperatorContext operatorContext = driverContext.addOperatorContext(operatorId, planNodeId, HashSemiJoinOperator.class.getSimpleName());
            return new WorkProcessorOperatorAdapter(operatorContext, this);
        }