presto-spi/src/main/java/io/prestosql/spi/block/AbstractSingleRowBlock.java/AbstractSingleRowBlock/getSlice
class AbstractSingleRowBlock:    @Override
    public Slice getSlice(int position, int offset, int length)
    {
        checkFieldIndex(position);
        return getRawFieldBlock(position).getSlice(rowIndex, offset, length);
    }