Symfony version(s) affected: 4.2.7

Description
SyliusThemeBundle overrides default translator service with the one that implements Symfony\Component\Translation\TranslatorInterface but not Symfony\Contracts\Translation\TranslatorInterface. This causes Symfony\Component\Validator\Util\LegacyTranslatorProxy to fail because it expects translator service to implement the contract's translator interface. It is a BC break AFAIK.

https://travis-ci.org/Sylius/Sylius/jobs/521619940#L834

How to reproduce
Override translator service not to implement Symfony\Contracts\Translation\TranslatorInterface but Symfony\Component\Translation\TranslatorInterface instead.

Possible Solution

• make Symfony\Component\Translation\TranslatorInterface extend Symfony\Contracts\Translation\TranslatorInterface
• allow Symfony\Component\Translation\TranslatorInterface instance to be passed to Symfony\Component\Validator\Util\LegacyTranslatorProxy