Currently certain objects (e.g. entity) are passed by reference in some places and passed by ID (e.g. other_entity) in some other places which are then resolved using an object registry (e.g. IPA.get_entity(<entity ID>)). Each method has advantages depending on the situation (e.g. object declaration, implementation, or unit tests), so the code should be modified to support both methods at the same time.

One solution is to modify the registry function to accept both data types. If it's an ID it will resolve the object and return it. If it's a reference it will return the reference itself.