Handle stubs

[Gabriel-Darbord]

Stubs lack the information required by the exporter to faithfully recreate the object.
In particular:

• attributes are unknown
• most method data is missing, we know about the methods that are called but they are also stubs so we don't know the parameters

Not sure how to handle such cases yet.

[NicolasAnquetil]

maybe in this case we should rely on serialization/de-serailization in the test.
You could create a special method with no parameter that returns directly the deserialized object (and the method would contain the serialization string) ...

??