Bugfix
This is a problem if in a model.
#!plantuml @startuml A *-- "1..*" B : bs @enduml
has an instance of A`, wants to delete it, but wants to save the instance of B associated with it. To do this, you must detach `B from A` before deleting `A. But this detaching is currently not possible with a mandatory attribute(bs), because the attribute does not accept an empty value (even temporarily).
Test
- test.com.top_logic.element.meta.TestClearMandatoryAttribute.testClearAttribute()