presto-main/src/main/java/io/prestosql/split/MappedPageSource.java/MappedPageSource/MappedPageSource
class MappedPageSource:    public MappedPageSource(ConnectorPageSource delegate, List<Integer> delegateFieldIndex)
    {
        this.delegate = requireNonNull(delegate, "delegate is null");
        this.delegateFieldIndex = Ints.toArray(requireNonNull(delegateFieldIndex, "delegateFieldIndex is null"));
    }