hotfix custom barcode adapter wasn't being set to options.

since it was only setting the adapter to $this->options in line 11, and there was an if to check if the adapter was a string in line 3, the adapter were never going to be set to options if the param provided was an object.

This should be checking if `$adapter` is an object before calling `get_class`. The common pattern we use is:

```php
(is_object($adapter) ? get_class($adapter) : gettype($adapter)
```