ConcurrentModificationException when scanning Channels and Operations

[madsvcarlsen]

Describe the bug
When I launch Spring, a concurrentmodificationexceptions arethrown, with null as the error message.
This happens for channel scanning as well as operation scanning. As a result, there are no channels or operations in the resulting AsyncAPI document. If it has any relevance, I am using SpEL to define my topic names, accessing an enum value. Changing

Dependencies and versions used

• springwolf-kafka version 1.11.0
• springwolf-ui version 1.11.0
• org.springframework.boot version 3.4.3
• spring-modulith-starter-core version 1.3.3
• org.springdoc:springdoc-openapi-starter-webmvc-ui version 2.8.5

Code example
No relevant snippets available, just described a kafka listener.
Currently there is only one Listener and one producer in the project.

Stack trace and error logs

2025-03-08T19:53:54.657+01:00 ERROR 21904 --- [***-backend-modulith] [main] i.g.s.c.a.o.DefaultOperationsService     : An error was encountered during operation scanning with io.github.springwolf.core.asyncapi.scanners.operations.OperationsInClassScannerAdapter@26159658: null

java.util.ConcurrentModificationException: null
	at java.base/java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:1023) ~[na:na]
	at java.base/java.util.LinkedHashMap$LinkedValueIterator.next(LinkedHashMap.java:1052) ~[na:na]
	at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133) ~[na:na]
	at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1939) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[na:na]
	at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151) ~[na:na]
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[na:na]
	at io.github.springwolf.core.asyncapi.schemas.SwaggerSchemaService.processCommonModelConverters(SwaggerSchemaService.java:114) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.schemas.SwaggerSchemaService.preProcessSchemas(SwaggerSchemaService.java:105) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.schemas.SwaggerSchemaService.resolveSchema(SwaggerSchemaService.java:94) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.components.DefaultComponentsService.resolvePayloadSchema(DefaultComponentsService.java:33) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.scanners.common.payload.internal.PayloadService.buildSchema(PayloadService.java:43) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.scanners.common.payload.internal.PayloadService.buildSchema(PayloadService.java:36) ~[springwolf-core-1.11.0.jar:na]
	at java.base/java.util.Optional.map(Optional.java:260) ~[na:na]
	at io.github.springwolf.core.asyncapi.scanners.common.payload.PayloadMethodParameterService.extractSchema(PayloadMethodParameterService.java:20) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.scanners.operations.annotations.SpringAnnotationMethodLevelOperationsScanner.mapMethodToOperation(SpringAnnotationMethodLevelOperationsScanner.java:38) ~[springwolf-core-1.11.0.jar:na]
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) ~[na:na]
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) ~[na:na]
	at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133) ~[na:na]
	at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1939) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[na:na]
	at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151) ~[na:na]
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$15$1.accept(ReferencePipeline.java:541) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) ~[na:na]
	at java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:1024) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[na:na]
	at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151) ~[na:na]
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) ~[na:na]
	at java.base/java.util.HashMap$KeySpliterator.forEachRemaining(HashMap.java:1715) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:575) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipeline.java:260) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:616) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:622) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.toList(ReferencePipeline.java:627) ~[na:na]
	at io.github.springwolf.core.asyncapi.scanners.operations.OperationsInClassScannerAdapter.mapToOperations(OperationsInClassScannerAdapter.java:30) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.scanners.operations.OperationsInClassScannerAdapter.scan(OperationsInClassScannerAdapter.java:24) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.operations.DefaultOperationsService.findOperations(DefaultOperationsService.java:34) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.DefaultAsyncApiService.initAsyncAPI(DefaultAsyncApiService.java:86) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.asyncapi.DefaultAsyncApiService.getAsyncAPI(DefaultAsyncApiService.java:44) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.SpringwolfInitApplicationListener.onApplicationEvent(SpringwolfInitApplicationListener.java:31) ~[springwolf-core-1.11.0.jar:na]
	at io.github.springwolf.core.SpringwolfInitApplicationListener.onApplicationEvent(SpringwolfInitApplicationListener.java:17) ~[springwolf-core-1.11.0.jar:na]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:185) ~[spring-context-6.2.1.jar:6.2.1]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:178) ~[spring-context-6.2.1.jar:6.2.1]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:156) ~[spring-context-6.2.1.jar:6.2.1]
	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:454) ~[spring-context-6.2.1.jar:6.2.1]
	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:387) ~[spring-context-6.2.1.jar:6.2.1]
	at org.springframework.boot.context.event.EventPublishingRunListener.ready(EventPublishingRunListener.java:109) ~[spring-boot-3.4.1.jar:3.4.1]
	at org.springframework.boot.SpringApplicationRunListeners.lambda$ready$6(SpringApplicationRunListeners.java:80) ~[spring-boot-3.4.1.jar:3.4.1]
	at java.base/java.lang.Iterable.forEach(Iterable.java:75) ~[na:na]
	at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:118) ~[spring-boot-3.4.1.jar:3.4.1]
	at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:112) ~[spring-boot-3.4.1.jar:3.4.1]
	at org.springframework.boot.SpringApplicationRunListeners.ready(SpringApplicationRunListeners.java:80) ~[spring-boot-3.4.1.jar:3.4.1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:332) ~[spring-boot-3.4.1.jar:3.4.1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1361) ~[spring-boot-3.4.1.jar:3.4.1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1350) ~[spring-boot-3.4.1.jar:3.4.1]
	at ***.SpringModulith.main(SpringModulith.java:22) ~[main/:na]

[github-actions]

Welcome to Springwolf. Thanks a lot for reporting your first issue. Please check out our contributors guide and feel free to join us on discord.

[timonback]

Hi @madsvcarlsen,
Thank you for the report.

I suspect, you are using model converters and there is a bug that is trigged in some instances.
A solution is provided in #1223.

Next step is the PR review, which will probably happen on Friday.

[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!