NPE on Json sub type with no name defined

[lwielek]

During OpenAPI object creation, the jackson model resolver fails with NPE (swagger-core 2.0.2):

at io.swagger.v3.core.jackson.ModelResolver.resolveSubtypes(ModelResolver.java:1087)
at io.swagger.v3.core.jackson.ModelResolver.resolve(ModelResolver.java:642)

Fails on JsonSubType wit null/empty name, example:

@com.fasterxml.jackson.annotation.JsonTypeInfo(use = com.fasterxml.jackson.annotation.JsonTypeInfo.Id.NAME, include = com.fasterxml.jackson.annotation.JsonTypeInfo.As.WRAPPER_OBJECT)
@com.fasterxml.jackson.annotation.JsonSubTypes({
        @com.fasterxml.jackson.annotation.JsonSubTypes.Type(value = ExampleSubType.class)})
public interface Example {
//...
}

public enum ExampleSubType implements Example {
//...

[frantuma]

Seems not to be reproducible, can you share the full failing resource/model class and the caller code, and possibly the full stack trace?

[lwielek]

@frantuma
source attached

issue.2862.zip

full stack trace:

Exception in thread "main" java.lang.NullPointerException
	at io.swagger.v3.core.jackson.ModelResolver.resolveSubtypes(ModelResolver.java:1106)
	at io.swagger.v3.core.jackson.ModelResolver.resolve(ModelResolver.java:679)
	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:949)
	at io.swagger.v3.jaxrs2.Reader.parseMethod(Reader.java:754)
	at io.swagger.v3.jaxrs2.Reader.read(Reader.java:422)
	at io.swagger.v3.jaxrs2.Reader.read(Reader.java:169)
	at io.swagger.v3.jaxrs2.Reader.read(Reader.java:196)
	at io.swagger.v3.oas.integration.GenericOpenApiContext.read(GenericOpenApiContext.java:353)
	at example.main.Main.main(Main.java:23)

[frantuma]

Thanks, issue was indeed with enums in combination with subtypes compound models; not really sure what the example models represent, however #2878 fixes the NPE for such scenario; the outcome for the given example would be:

Example:
  type: object
ExampleSubType:
  type: string
  allOf:
  - $ref: '#/components/schemas/Example'
  enum:
  - VALUE1
  - VALUE2

closing ticket, please reopen if you're still experiencing issues

[lwielek]

@frantuma thanks! looking forward for a release containing this fix

[lwielek]

@frantuma
There's another issue, I spotted here.
The JsonTypeInfo.As.WRAPPER_OBJECT is not handled correctly in the OpenAPI model.
With the wrapper object annotation, the enum is serialized as an object, not as a simple string.
Example:

{"ExampleSubType":"VALUE1"}