All files under the Tests directory are now correctly handled as internal test classes.
You can't extend them anymore, because they are only loaded when running internal tests.
More information can be found in the composer docs.
The Sonata\TranslationBundle\Traits\Translatable class is deprecated.
Use Sonata\TranslationBundle\Traits\TranslatableTrait instead.
The Sonata\TranslationBundle\Traits\PersonalTranslatable class is deprecated.
Use Sonata\TranslationBundle\Traits\PersonalTranslatableTrait instead.