AspectJ proxy bean gives IllegalAccessException in Java 16

Here is a sample project which demonstrates the issue with SB 2.4 and JDK 16 https://github.com/EvgeniGordeev/spring-boot-java-16-aspectj-proxy-error.

The application cannot start due to:

Caused by: java.lang.IllegalAccessException: module java.base does not open java.lang to unnamed module @11dc3715
	at java.base/java.lang.invoke.MethodHandles.privateLookupIn(MethodHandles.java:260) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78) ~[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:567) ~[na:na]
	at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:574) ~[spring-core-5.3.6.jar:5.3.6]
	... 23 common frames omitted

Valid for beans with @Transactional and when SpringBootApplication combines @EnableAspectJAutoProxy and @EnableTransactionManagement.

[philwebb]

I’m going to transfer this one to the Spring Framework team for assessment. Spring Boot isn’t actually involved in the proxy creation, it’s a framework concern. This looks similar to https://github.com/spring-projects/spring-framework/issues/26440 but there’s no module-info involved in your sample.

[wilkinsona]

I’m not sure how we can fix this one either. In this case contextClass is java.lang.Object so getClassLoader() returns null. The loader argument is the app class loader (jdk.internal.loader.ClassLoaders$AppClassLoader).

As far as I can tell, the failure is specific to proxying of methods defined in the JDK such as Object#toString which is the method being called in the sample. Calling testMethod() on the proxied service doesn’t trigger the problem and works fine (once the sample’s dependencies have been updated a little so that a transaction manager is auto-configured).