The controllers should allow TranslationInterface from the component too

[Nyholm]

Currently we only allow TranslationInterface from Contracts. We should allow the same interface from the component too.

Symfony 3.4 is not using contracts.

[rvanlaak]

Would adding a class_alias be sufficient?

https://github.com/symfony/translation/blob/3.4/TranslatorInterface.php

https://github.com/symfony/translation-contracts/blob/master/TranslatorInterface.php

[rvanlaak]

The controller uses translations for the exception messages. The exception messages will not be visible to users, as on prod the exception message will not get shown.

In other words; the translations in the controller and the translation files can get removed, and thereby the dev dependency on symfony/translation also can get removed.