presto-spi/src/main/java/io/prestosql/spi/block/AbstractRowBlock.java/AbstractRowBlock/getObject
class AbstractRowBlock:    @Override
    public <T> T getObject(int position, Class<T> clazz)
    {
        if (clazz != Block.class) {
            throw new IllegalArgumentException("clazz must be Block.class");
        }
        checkReadablePosition(position);

        return clazz.cast(new SingleRowBlock(getFieldBlockOffset(position), getRawFieldBlocks()));
    }