Add config-override for @JsonTypeInfo.Value

[JooHyukKim]

• part of Allow introspection and config-override system to use JsonTypeInfo.Value #3943

[cowtowncoder]

Ok this is unfortunately problematic in couple of ways:

1. It uses less specific (parent) information if both exist (should prefer specific one)
2. Assumes 2 levels of inheritance (could have more)
3. For interfaces getSuperClass() returns null I think? I don't think this would work when base type is interface

It is also different from all other config overrides which only consider exact baseType passed. I think that'd be correct thing to do here -- except I suspect there was a problem wrt serialization side: on deserialization one usually specifies proper base type (to get to polymorphic subtype). But on serialization, unfortunately, the way things are "baseType" is probably actual implementation type.
So using just that might not work.

If so I am not sure if this can actually be made to work, without fixing more fundamental problem: Jackson really should find proper base type on serialization too and not rely on annotation inheritance (which is why things work at all wrt @JsonTypeInfo).

[JooHyukKim]

But on serialization, unfortunately, the way things are "baseType" is probably actual implementation type. So using just that might not work.

Ah, okay. So this was what bothered me, but couldn't figure out why 😅. I should double check, if I remember correctly, the getSuperClass() checking was needed on the serialization side.

[JooHyukKim]

problem: Jackson really should find proper base type on serialization too and not rely on annotation inheritance

@cowtowncoder Hmm unless there is a work going on about this, someday probably I will make time tacle this (or together if any). May I bring this up after your vacation (congrats😆)

[cowtowncoder]

Ok so I am bit worried about that issue I mentioned wrt locating ConfigOverride to use: I think it should not try to traverse inheritance hierarchy due to complexity. If you only look at specific baseType would that work? (I am guessing not, due to serialization side not passing true base type, but I might be wrong)

[JooHyukKim]

.... traverse inheritance hierarchy due to complexity. If you only look at specific baseType would that work?

At this point, I doubt.

Ok so I am bit worried about that issue I mentioned wrt locating ConfigOverride to use: I think it should not try to traverse inheritance hierarchy due to complexity.

Agreed, it seems like a dangerous path down 🙃... I will try to find cleaner way --plus after refering to other config-override mechanisms, it "might" be possible to make use of AnnotatedClass, just like MapperConfig.getDefaultPropertyInclusions(Class<?>, AnnotatedClass); to introspect in Jackson-style 👍🏻👍🏻

[JooHyukKim]

Temporarily drafted

Will turn into draft until un-natural introspection at #3959 (comment) is resolved.

[JooHyukKim]

Closing this as part of clean up, until solution is found 🙏🏼

[JooHyukKim]

The changed part since review #3959 (comment). Here we traverse using ClassUtil.findSuperTypes() that supports both concrete types and interfaces.

EDIT : Traversal is to complement serialization side not locating the "exact" baseType.

WDYT? /cc @cowtowncoder

[JooHyukKim]

Closing for now. Because of low user demand AND 2.16-rc is released.