presto-spi/src/main/java/io/prestosql/spi/block/AbstractVariableWidthBlock.java/AbstractVariableWidthBlock/getByte
class AbstractVariableWidthBlock:    @Override
    public byte getByte(int position, int offset)
    {
        checkReadablePosition(position);
        return getRawSlice(position).getByte(getPositionOffset(position) + offset);
    }