ref on an NSObject returns a private type

[stuartmorgan-g]

All NSObjects extend NSObject, which extends objc.ObjCObjectBase, which extends _ObjCRefHolder<c.ObjCObject, _ObjCObjectRef>, which declares a public ref getter:

class _ObjCRefHolder<T extends NativeType, Ref extends _ObjCReference<T>> {
  final Ref ref;

So every object has a ref property that returns a _ObjCObjectRef, which makes it annoying to mock with mockito (similar to also #1861):

Invalid @GenerateMocks annotation: Mockito cannot generate a valid mock class which implements 'NSBundle' for the following reasons:
    The property accessor '_ObjCRefHolder.ref' features a private return type, and cannot be stubbed. Try generating this mock with a MockSpec with 'unsupportedMembers' or a dummy generator (see https://pub.dev/documentation/mockito/latest/annotations/MockSpec-class.html).