This sample is based on the usage of the https://github.com/KnpLabs/DoctrineBehaviors#translatable

So here, Gender.translations is not a flat array but a Doctrine Array Collection of GenderTranslation with the locale as key of the collection.

I would like just show that it's possible to use a path which is supported by the Property Access component here. Maybe I can add a link to the KnpLabs DoctrineBehaviors to give more information on the context?