removeObserver method
Removes name
and its associated PolicySubject from
the observer
group.
Returns the PolicySubject associated with name
before it was removed.
Returns null
if name
was no observer
or there is no
observer
group.
Implementation
PolicySubject? removeObserver(String name) {
if (!_groups.containsKey(observerGroupKey)) return null;
final PolicyGroup observer = _groups[observerGroupKey]!;
return observer.subjects.remove(name);
}