NullPointerException when executing all test

[ccudennec-otto]

Describe the bug
I use a standalone test to generate my AsyncAPI documentation. When I execute the test standalone, everything works fine. But if I run all my tests, I get a NullPointerException when the proper type of a property is identified:

This error was probably caused by the recent code changes: #1416

Dependencies and versions used

• springwolf-kafka version 1.19.0

Code example
I can grant you code access company internally if it helps.

Stack trace and error logs

2025-11-03 07:15:22,307 ERROR logger="io.github.springwolf.core.asyncapi.channels.DefaultChannelsService" message="An error was encountered during channel scanning with io.github.springwolf.core.asyncapi.scanners.channels.ChannelsInClassScannerAdapter@2d0c1399: null" thread="Test worker"  
java.lang.NullPointerException: null
  at java.base/java.util.Objects.requireNonNull(Objects.java:233)
  at java.base/java.util.ImmutableCollections$Set12.<init>(ImmutableCollections.java:790)
  at java.base/java.util.Set.of(Set.java:470)
  at io.github.springwolf.asyncapi.v3.model.schema.SchemaObject$SchemaObjectBuilder.type(SchemaObject.java:165)
  at io.github.springwolf.core.asyncapi.schemas.SwaggerSchemaUtil.assignType(SwaggerSchemaUtil.java:189)
  at io.github.springwolf.core.asyncapi.schemas.SwaggerSchemaUtil.mapSchema(SwaggerSchemaUtil.java:75)

I can see that this error is also shown in the test output when the documentation generation is triggered by SpringwolfInitApplicationListener. Does this point to some kind of race condition?

[timonback]

Original cause seems to be a missing @Schema(oneof=...) annotation when @JsonSubTypes is used.

Using the blister of #1507, only the NullPointerException is avoided.
However, Springwolf ignores the @JsonSubTypes information.
If you encounter this issue, you probably want to add the @Schema annotation, like:

@Schema(oneOf = {VehicleElectricPayloadDto.class, ...})

Recommended usage:

springwolf-core/springwolf-examples/springwolf-kafka-example/src/main/java/io/github/springwolf/examples/kafka/dtos/discriminator/VehicleBase.java

Lines 12 to 18 in ef4e47a

	@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "vehicleType")
	@JsonSubTypes({
	@JsonSubTypes.Type(value = VehicleElectricPayloadDto.class, name = "VehicleElectricPayloadDto"),
	@JsonSubTypes.Type(value = VehicleGasolinePayloadDto.class, name = "VehicleGasolinePayloadDto"),
	})
	@Schema(
	oneOf = {VehicleElectricPayloadDto.class, VehicleGasolinePayloadDto.class},

[github-actions]

The change is staged for release and will be part of the next release.

If you want to try and verify it in your application today,
use the latest 1.X.0-SNAPSHOT build as described in our README.md > Testing SNAPSHOT version

Thank you for the report/contribution!

[ccudennec-otto]

Hi @timonback !

Thanks for looking into this!

However, Springwolf ignores the @JsonSubTypes information.

So, this could be a future improvement?

The change is staged for release and will be part of the next release.

Will you publish an extra release or just publish it in the regular release cycle?

Thanks!

Christopher

[timonback]

Hi @ccudennec-otto ,

We might consider it as a contribution, but are unsure due to the complexity of implementing it correctly and direct coupling to another library (Jackson).
I see also options for instead of auto-detecting the configuration, to add a validator/linter that warns on mismatching configurations.
Still, this is best discussed in a dedicated issue.

Personally, I would stick with the monthly release cycle. The bug fix just hides a technical error caused by mismatch of JsonSubTypes and Schema annotation. When both annotations are aligned, no exception is thrown in the current version.

[ccudennec-otto]

Should we wait for the release to close the issue or can I close it already?

[timonback]

We close the issue when the release is there to communicate which issues have been fixed, but are not available yet