Getter dispatch in case of default value in K3

[fcoulon]

For the case:

• An EClass containing an attribute foo
• An Aspect over this class declaring foo with a default value Can we consider the aspect has the priority?

It is breaking a test case in Melange. We load a model of merged Ecore + Aspect and try to access the attribute declared in the Aspect but we access the null value of the model.

https://github.com/diverse-project/k3/blob/5c35a839cdf9528d444b5c1d3afa168c585d7615/k3.eclipse/fr.inria.diverse.k3.al.annotationprocessor.plugin/src/fr/inria/diverse/k3/al/annotationprocessor/Aspect.xtend#L800-L817