presto-main/src/main/java/io/prestosql/operator/index/UnloadedIndexKeyRecordSet.java/UnloadedIndexKeyRecordCursor/UnloadedIndexKeyRecordCursor
class UnloadedIndexKeyRecordCursor:        public UnloadedIndexKeyRecordCursor(List<Type> types, List<PageAndPositions> pageAndPositions)
        {
            this.types = ImmutableList.copyOf(requireNonNull(types, "types is null"));
            this.pageAndPositionsIterator = requireNonNull(pageAndPositions, "pageAndPositions is null").iterator();
        }