Hi @Mattias-Sehlstedt! Thank you for working on improving the code in Swagger Core once again.
We appreciate a lot any intent to make the Model Resolver any smaller :) That's definitely something that needs to be done.

One issue that I see with this refactor is that it is creating a new public API and it seems unintentional. DiscriminatorUtils is public, and both methods are public static methods. Once released, consumers may treat these methods as supported API, creating future compatibility obligations.

The DiscriminatorUtils in this form does not establish a strong public use case. I would keep it internal.

Please consider moving it in the io.swagger.v3.core.jackson package and making it package-private.

I have moved it to the jackson package and made it package private. I have also added a private constructor to align it with the already existing "utils" class there (JAXBAnnotationsHelper). Should it be renamed to Helper too? I personally find Utils to be the more common and descriptive naming pattern.

The other common pattern is to utilize JavaDoc to explicitly state that the signature is volatile/subject to change/internal. But I could not find that the project has done that before so a bit odd to start with it now.

@Mattias-Sehlstedt thank you for carrying out these changes. Since the project does not use JavaDoc annotations I do not see any reason to introduce it here. I would argue that even Resolver instead of Util would make sense here, but I am fine with merging it as it is.

I agree with the suggestion of changing it to Resolver and have adjusted to that. It makes it clearer that the ModelResolver is itself a resolver of resolvers that handle sub-subjects.

It also aligns well with the fact that there already is one such complex area that has been isolated to its own Resolver (TypeNameResolver).