Spring `superinterface check failed` when using Java modules (for Axon Framework Spring Boot app)

Question

I am currently experimenting with Spring Boot, the Axon Framework and java modules (using JDK 17).

I have created a repo to illustrate the problem: here

The problem is that the application does not start and I get the exception as follows:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'accountViewProjection' defined in file [C:\workspace\axon\_issue_replication_repos\axon-module-error\axon-example-app\build\classes\java\main\io\github\vab2048\axon\example_bug\app\query\account\AccountViewProjection.class]: Initialization of bean failed; nested exception is org.springframework.aop.framework.AopConfigException: Could not generate CGLIB subclass of class io.github.vab2048.axon.example_bug.app.query.account.AccountViewProjection: Common causes of this problem include using a final class or a non-visible class; nested exception is org.springframework.cglib.core.CodeGenerationException: java.lang.IllegalAccessError-->superinterface check failed: class io.github.vab2048.axon.example_bug.app.query.account.AccountViewProjection$$EnhancerBySpringCGLIB$$159eee6a (in module io.github.vab2048.axon.example_bug.app) cannot access class org.springframework.aop.framework.Advised (in unnamed module @0x732d0d24) because module io.github.vab2048.axon.example_bug.app does not read unnamed module @0x732d0d24
    at spring.beans@5.3.20/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:628) ~[spring-beans-5.3.20.jar:na]
    at spring.beans@5.3.20/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.20.jar:na]
    at spring.beans@5.3.20/org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.20.jar:na]
    at spring.beans@5.3.20/org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.20.jar:na]
    at spring.beans@5.3.20/org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.20.jar:na]
    at spring.beans@5.3.20/org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.20.jar:na]
    at spring.beans@5.3.20/org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:953) ~[spring-beans-5.3.20.jar:na]
    at spring.context@5.3.20/org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.20.jar:na]
    at spring.context@5.3.20/org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.20.jar:na]
    at spring.boot@2.7.0/org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147) ~[spring-boot-2.7.0.jar:na]
    at spring.boot@2.7.0/org.springframework.boot.SpringApplication.refresh(SpringApplication.java:734) ~[spring-boot-2.7.0.jar:na]
    at spring.boot@2.7.0/org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408) ~[spring-boot-2.7.0.jar:na]
    at spring.boot@2.7.0/org.springframework.boot.SpringApplication.run(SpringApplication.java:308) ~[spring-boot-2.7.0.jar:na]
    at spring.boot@2.7.0/org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) ~[spring-boot-2.7.0.jar:na]
    at spring.boot@2.7.0/org.springframework.boot.SpringApplication.run(SpringApplication.java:1295) ~[spring-boot-2.7.0.jar:na]
    at io.github.vab2048.axon.example_bug.app/io.github.vab2048.axon.example_bug.app.AxonApplication.main(AxonApplication.java:10) ~[main/:na]
Caused by: org.springframework.aop.framework.AopConfigException: Could not generate CGLIB subclass of class io.github.vab2048.axon.example_bug.app.query.account.AccountViewProjection: Common causes of this problem include using a final class or a non-visible class; nested exception is org.springframework.cglib.core.CodeGenerationException: java.lang.IllegalAccessError-->superinterface check failed: class io.github.vab2048.axon.example_bug.app.query.account.AccountViewProjection$$EnhancerBySpringCGLIB$$159eee6a (in module io.github.vab2048.axon.example_bug.app) cannot access class org.springframework.aop.framework.Advised (in unnamed module @0x732d0d24) because module io.github.vab2048.axon.example_bug.app does not read unnamed module @0x732d0d24
    at org.springframework.aop.framework.CglibAopProxy.getProxy(CglibAopProxy.java:209) ~[spring-aop-5.3.20.jar:5.3.20]
    at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:110) ~[spring-aop-5.3.20.jar:5.3.20]
    at org.axonframework.spring@4.5.9/org.axonframework.spring.config.AbstractAnnotationHandlerBeanPostProcessor.createAdapterProxy(AbstractAnnotationHandlerBeanPostProcessor.java:190) ~[axon-spring-4.5.9.jar:na]
    at org.axonframework.spring@4.5.9/org.axonframework.spring.config.AbstractAnnotationHandlerBeanPostProcessor.postProcessAfterInitialization(AbstractAnnotationHandlerBeanPostProcessor.java:89) ~[axon-spring-4.5.9.jar:na]
    at spring.beans@5.3.20/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:455) ~[spring-beans-5.3.20.jar:na]
    at spring.beans@5.3.20/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1808) ~[spring-beans-5.3.20.jar:na]
    at spring.beans@5.3.20/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:620) ~[spring-beans-5.3.20.jar:na]
    ... 15 common frames omitted
Caused by: org.springframework.cglib.core.CodeGenerationException: java.lang.IllegalAccessError-->superinterface check failed: class io.github.vab2048.axon.example_bug.app.query.account.AccountViewProjection$$EnhancerBySpringCGLIB$$159eee6a (in module io.github.vab2048.axon.example_bug.app) cannot access class org.springframework.aop.framework.Advised (in unnamed module @0x732d0d24) because module io.github.vab2048.axon.example_bug.app does not read unnamed module @0x732d0d24
    at spring.core@5.3.20/org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:512) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:363) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.proxy.Enhancer.generate(Enhancer.java:585) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:110) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:108) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54) ~[spring-core-5.3.20.jar:na]
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[na:na]
    at spring.core@5.3.20/org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.core.internal.LoadingCache.get(LoadingCache.java:34) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:134) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:319) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.proxy.Enhancer.createHelper(Enhancer.java:572) ~[spring-core-5.3.20.jar:na]
    at spring.core@5.3.20/org.springframework.cglib.proxy.Enhancer.createClass(Enhancer.java:419) ~[spring-core-5.3.20.jar:na]
    at org.springframework.aop.framework.ObjenesisCglibAopProxy.createProxyClassAndInstance(ObjenesisCglibAopProxy.java:57) ~[spring-aop-5.3.20.jar:5.3.20]
    at org.springframework.aop.framework.CglibAopProxy.getProxy(CglibAopProxy.java:206) ~[spring-aop-5.3.20.jar:5.3.20]
    ... 21 common frames omitted
Caused by: java.lang.IllegalAccessError: superinterface check failed: class io.github.vab2048.axon.example_bug.app.query.account.AccountViewProjection$$EnhancerBySpringCGLIB$$159eee6a (in module io.github.vab2048.axon.example_bug.app) cannot access class org.springframework.aop.framework.Advised (in unnamed module @0x732d0d24) because module io.github.vab2048.axon.example_bug.app does not read unnamed module @0x732d0d24
    at java.base/java.lang.ClassLoader.defineClass0(Native Method) ~[na:na]
    at java.base/java.lang.System$2.defineClass(System.java:2307) ~[na:na]
    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2439) ~[na:na]
    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2416) ~[na:na]
    at java.base/java.lang.invoke.MethodHandles$Lookup.defineClass(MethodHandles.java:1843) ~[na:na]
    at java.base/jdk.internal.reflect.GeneratedMethodAccessor33.invoke(Unknown Source) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
    at spring.core@5.3.20/org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:507) ~[spring-core-5.3.20.jar:na]
    ... 35 common frames omitted

The offending code seems to to be in io.github.vab2048.axon.example_bug.app.query.account.AccountViewProjection :

    @QueryHandler
    public AccountView getAccount(GetAccountView query) {
        log.debug("Handling: {}", query);
        return repository.findById(query.id()).orElseThrow();
    }

It is the Axon annotation @QueryHandler which causes it (you can verify this by commenting it out and then everything works). This is strange because none of the other Axon annotations cause this problem. The package itself is both exported and open in the module-info.java file.

What am I doing wrong? I am aware there may be command line arguments which may be added to solve this issue but am not sure what exactly to use (ideally I shouldn't have to give any command line arguments at all).

Answer 1

I am somewhat in doubt about posting this as an answer, but I will do it regardless.

Have you tried removing Spring AOP from the mix? It seems like Spring AOP is making some inner classes that cause the IllegalAccessError , not so much Axon Framework.

If this solves the issue, I'd wager there's something to be done with Spring AOP to make this work. Sadly, this isn't my forte, so I'd have to investigate what kind of settings, if any, would help in that perspective.