presto-main/src/main/java/io/prestosql/operator/WorkProcessorPipelineSourceOperator.java/WorkProcessorPipelineSourceOperatorFactory/WorkProcessorPipelineSourceOperatorFactory
class WorkProcessorPipelineSourceOperatorFactory:        private WorkProcessorPipelineSourceOperatorFactory(
                int operatorId,
                WorkProcessorSourceOperatorFactory sourceOperatorFactory,
                List<WorkProcessorOperatorFactory> operatorFactories)
        {
            this.operatorId = operatorId;
            this.sourceOperatorFactory = requireNonNull(sourceOperatorFactory, "sourceOperatorFactory is null");
            this.operatorFactories = requireNonNull(operatorFactories, "operatorFactories is null");
        }