Make ActiveResourceSpecification an abstract base class
In the current meta-model version ActionResourceSpecification inherits from ConfigurationSpecification and has two containment references to ProcessingResourceSpecification and LinkingResourceSpecification. Although the naming suggests that the latter ones are also ConfigurationSpecifications they do not inherit from the base class. The current situation is confusing since I can specify different ActiveResourceSpecifications with different ProcessingResourceSpecification or only use one ActiveResourceSpecification containing all the others. Both are equivalent.
In order to improve the clearness of the meta-modell, change ActiveResourceSpecification to abstract class and let ProcessingResourceSpecificationLinkingResourceSpecification inherit from it.