presto-spi/src/main/java/io/prestosql/spi/block/LazyBlock.java/RegionLazyBlockLoader/RegionLazyBlockLoader
class RegionLazyBlockLoader:        public RegionLazyBlockLoader(LazyData delegate, int positionOffset, int length)
        {
            this.delegate = requireNonNull(delegate, "delegate is null");
            this.positionOffset = positionOffset;
            this.length = length;
        }