### Description This works with yaml ```yaml App\Example: calls: - method: addOptions arguments: - key_1: "value_1" !php/const App\Example::CONSTANT_1: 'value_0' ``` I can use constant in a collection entry key. I'd like to use the same with XML config. ### Example Currently I can use constant for value but not a key ```xml <argument type="collection"> <argument type="constant" key="Symfony\Component\Serializer\Normalizer\DateTimeNormalizer::FORMAT_KEY">DATE_ATOM</argument> </argument ```