Class loader issues with IBM Open Liberty server

In combination with IBM Open Liberty server, I've encountered two problems with Spring Modulith:

1. Application startup fails with org.springframework.cglib.core.CodeGenerationException: java.lang.IllegalAccessError-->class org.springframework.modulith.events.jdbc.JdbcEventPublicationRepository$$SpringCGLIB$$0 cannot access its superclass org.springframework.modulith.events.jdbc.JdbcEventPublicationRepository.
2. Uninitialized member variables in Service component with a @ApplicationModuleListener annotated method to consume events cause NullPointerException when accessing said member variables.

While problem 1 can be bypassed with a patched "spring-modulith-events-jdbc-1.3.5.jar" where JdbcEventPublicationRepository is declared public instead of package-private, I don't understand yet the cause for problem 2. It's also possible that this monkey patch even triggers problem 2.

Since Open Liberty is not as common as other servers, I've prepared a small demo project.
The demo application mainly consists of:

• a Service EventProducer to publish events
• a Service EventConsumer that consumes the events (using @ApplicationModuleListener)
• a RestController EventController to trigger the event publication

Building the project with mvn verify will bundle Open Liberty as embedded server (instead of default Tomcat), so one does not require a standalone server installation. The README should hopefully contain enough details. Stack traces for both problems are also included.

I would like to emphasize that these issues only occur with Open Liberty as server runtime, but not with Tomcat. Open Liberty is known to do things differently thread-wise during bootstrapping than other servers (see Spring issue 34729).

Kind regards,
Thomas

Start with the linked demo project and its README, then run mvn verify to reproduce the two failures under embedded Open Liberty and compare the result with Tomcat. Review the included stack traces around JdbcEventPublicationRepository and the EventConsumer service. Done means identifying the cause of both class-loader or initialization problems and documenting or implementing a fix that works on Open Liberty without regressing Tomcat.