presto-main/src/main/java/io/prestosql/sql/planner/LocalExecutionPlanner.java/PhysicalOperation/PhysicalOperation
class PhysicalOperation:        public PhysicalOperation(OperatorFactory operatorFactory, Map<Symbol, Integer> layout, LocalExecutionPlanContext context, PhysicalOperation source)
        {
            this(operatorFactory, layout, context, Optional.of(requireNonNull(source, "source is null")), source.getPipelineExecutionStrategy());
        }