How to manage instanciation of out model when there is polymorphism

We do not control output models (for example lunatic-model) and sometimes they use polymorphism (for example `Questionnaire.getComponents()` is of type ComponentType which has many children). So when we instanciate an element for collections with this kind of types in out models, we must find a solution via annotations (not to break the mapping logical) to specify wich children instanciate (for example, when we instanciate an element to populate `Questionnaire.getComponents()`, we must find which implementation of `ComponentType`to use.

two solutions :
1. We should add annotation over eno model types to specify to which concrete out (also in ?) type they are mapped
2. we should add an attribute to the mappings annotations (for example @Lunatic) to specify to which concrete type a eno model element should be mapped at runtime. this attribute can be not mandatory.