Bring your own ObjectWriter to serialize the OpenAPI model

[gastaldi]

• Relates to Quarkus: Custom ObjectMapper  #1600

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

100.0% Coverage
0.0% Duplication

[MikeEdgar]

Unfortunately I don't think this will solve the issue. The main problem is that the scanner is introspecting a POJO with a field of type JsonNullable and it doesn't know how RestEasy will serialize that with a customized ObjectMapper. The scanner is building the OpenAPI model based on the Jandex types and the serialization of that model using a one-off ObjectMapper is separate from the RestEasy serialization of runtime instances of it.

I think a solution will need to either (1) make the annotation scanner aware of how a JsonNullable<T> should look or (2) make it something a user can configure.

For (1), it may just be that JsonNullable behaves like an Optional, which we already support.

For (2), we already have the mp.openapi.schema. config prefix, but I don't think it would work correctly with a generic type argument - that could be changed perhaps.

[gastaldi]

@MikeEdgar the solution I proposed here is to reuse an ObjectMapper that already has the required modules installed. The next step after this is released would be to change in Quarkus to pass the managed ObjectMapper that in @melloware's scenario is the one to be used.

Feel free to close this PR if that doesn't make sense

[MikeEdgar]

@gastaldi I think it makes sense to have a way for Quarkus to pass its ObjectMapper like this, so let's include this PR. I'll unlink the issue though because at the point the OpenAPI model is being serialized, it already contains the incorrect schema model introspected from the Jandex structure. In other words, the JsonNullable isn't in the model for serialization at this stage so having the Jackson module present for serialization won't impact the output.