NpE in ModelResolver

[mads-b]

Hello, I'm stuck at Swagger API 2.0 because upgrading the config to generate openapi v.3.0 (running swagger-core 2.0.9) results in the following exception when running:

[ERROR] Error resolving API specification java.lang.NullPointerException at io.swagger.v3.core.jackson.ModelResolver.resolve (ModelResolver.java:320) at io.swagger.v3.core.converter.ModelConverterContextImpl.resolve (ModelConverterContextImpl.java:90) at io.swagger.v3.core.jackson.ModelResolver.lambda$resolve$1 (ModelResolver.java:614) at io.swagger.v3.core.jackson.ModelResolver.resolve (ModelResolver.java:277) at io.swagger.v3.core.converter.ModelConverterContextImpl.resolve (ModelConverterContextImpl.java:90) at io.swagger.v3.core.jackson.ModelResolver.resolve (ModelResolver.java:622) at io.swagger.v3.core.converter.ModelConverterContextImpl.resolve (ModelConverterContextImpl.java:90) at io.swagger.v3.core.jackson.ModelResolver.resolve (ModelResolver.java:395) at io.swagger.v3.core.converter.ModelConverterContextImpl.resolve (ModelConverterContextImpl.java:90) at io.swagger.v3.core.jackson.ModelResolver.resolve (ModelResolver.java:363) at io.swagger.v3.core.converter.ModelConverterContextImpl.resolve (ModelConverterContextImpl.java:90) at io.swagger.v3.core.jackson.ModelResolver.resolve (ModelResolver.java:622) at io.swagger.v3.core.converter.ModelConverterContextImpl.resolve (ModelConverterContextImpl.java:90) at io.swagger.v3.core.converter.ModelConverters.resolveAsResolvedSchema (ModelConverters.java:112) at io.swagger.v3.jaxrs2.Reader.parseMethod (Reader.java:1020) at io.swagger.v3.jaxrs2.Reader.parseMethod (Reader.java:818)

Any ideas what's wrong/any fixes/workarounds? I've gotten quite "creative" using Jackson in this project, and in the sister project it works fine, so I suspect this is related to that rather creative bean that references a list of itself alongside having a @JsonUnwrapped member?

[frantuma]

Can you share the class/method causing the issue?

[mads-b]

At least this is my prime suspect.. Might be that links field as well; It has a polymorphic child, but that is not exactly uncommon in the Jackson world:

Links is a bean that has a @JsonValue method that returns a map, where the values are a superclass with two implementations.
HalBean.txt

[frantuma]

A possible co-culprit might be your shared bean using 1.5/x version (swagger/OpenAPI 2.0) of annotations, swagger-core 2.x supports a different set of annotations. You would need to update the bean to use the new set.

Additionally JsonSerialize.As is not yet supported in 3.0, see also #3288 (support should be part of upcoming release)

[mads-b]

We can rule out both those. The sister project I talked about uses that @JsonSerialize.as statement in all beans and somehow works (is that a fluke then, perhaps?), in addition I've tried porting all the beans over to the new annotation style without luck; It fails even without any openAPI annotations..

[frantuma]

playing a bit around for some reason this seemed to happen in scenarios with both JsonUnwrapped and Optional involved. Update in #3313 fixes the NPE, this is available in latest 2.0.10-SNAPSHOT and upcoming release.

[mads-b]

That's awesome! Lightning fast :-)

Thank you so much. I suppose I have a great deal to do very soon in order to port all the annotations over to v3..