presto-main/src/main/java/io/prestosql/operator/WorkProcessorSourceOperatorAdapter.java/WorkProcessorSourceOperatorAdapter/addSplit
class WorkProcessorSourceOperatorAdapter:    @Override
    public Supplier<Optional<UpdatablePageSource>> addSplit(Split split)
    {
        if (operatorFinishing) {
            return Optional::empty;
        }

        Object splitInfo = split.getInfo();
        if (splitInfo != null) {
            operatorContext.setInfoSupplier(() -> new SplitOperatorInfo(splitInfo));
        }

        splitBuffer.add(split);
        return sourceOperator.getUpdatablePageSourceSupplier();
    }