# service 'app.user_to_username'
<service id="app.user_to_username_transformer" class="AppBundle\Form\DataTransformer\UserToUsernameTransformer">
    <argument type="service" id="doctrine" />
</service>

# service 'fos_user.user_to_username_transformer
<service id="fos_user.user_to_username_transformer" alias="app.user_to_username_transformer" />


services:
    #..
    app.user_to_username:
        class: AppBundle\Form\DataTransformer\UserToUsernameTransformer
        arguments:
            - "@doctrine"
    fos_user.user_to_username:
        alias: app.user_to_username_transformer