TBH. I think that Payum should provide default storage info with `doctrine/orm`, and then you could just set:
```yaml
storages:
    Sylius\Bundle\CoreBundle\Model\Order: ~
    Sylius\Bundle\PaymentsBundle\Model\Payment: ~
```
Or something like that would be nice too:
```yaml
storages:
    Sylius\Bundle\CoreBundle\Model\Order: 'doctrine/orm'
    Sylius\Bundle\PaymentsBundle\Model\Payment: 'doctrine/orm'