Fixes #2399 : Adds defaultAnswer to the MockitoMockKey to distinguish the mock types, i.e. to separate mocks from spies otherwise spy type is reused for a mock or vice versa. - #2400

Ah, you will need to run ./gradlew spotlessApply locally to fix the formatting issues.

@TimvdLippe Pushed formatting fixes.

That's a bad patch, I'm afraid. Answer is an interface and most instances do not implement hashCode/equals, this effectively breaks the caching mechanism what can cause significant overhead. The problem is the fix for #2331 which we must roll back. Mocks and spies classes must not consider the default answer when created classes. This must be solved on the interceptor level. I see what I can do but generally, we should not have allowed for the exception on the object methods.

I also see that this created an inconsistency for the inline and subclass mock makers. I am not entirely sure why this restriction was ever introduced in Mockito, but if we want to remove it, we would need to remove it generally, not for spies only.

Oof, that's definitely on me for not fully understanding the domain space. Thanks Rafael for the additional knowledge, that was not something I was aware of. Reverting all the fixes seems like the right course of action at this point in time, to avoid further snowballing.

I still think the intent of #2331 is good (it caught numerous bad tests at Google), so I would like to figure out an alternative solution that does not have the downsides of the existing implementation.