Class loader issues with IBM Open Liberty server

[thegli]

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