ResponseEntityExceptionHandler with @ControllerAdvice is Ignored when using spring-modulith-observability

[bekaChichua]

Issue: ResponseEntityExceptionHandler with @ControllerAdvice is Ignored When Using spring-modulith-observability

Description

When spring-modulith-observability is included in the project dependencies, a custom class that extends ResponseEntityExceptionHandler and is annotated with @ControllerAdvice fails to catch exceptions as expected.

It appears that the exception handling flow is being disrupted, and the @ControllerAdvice is completely ignored.

From initial investigation, the issue seems to be related to the ModuleEntryInterceptor class. The interceptor wraps the controller method invocation (MethodInvocation.proceed()), and it appears to interfere with Spring MVC’s exception handling mechanism.

Steps to Reproduce

1.	Include spring-modulith-observability in your dependencies.
2.	Create a class that extends ResponseEntityExceptionHandler and annotate it with @ControllerAdvice.
3.	Throw an exception (e.g., RuntimeException) from a controller method.
4.	Observe that the exception is not handled by the custom exception handler.

Expected Behavior

•	The @ControllerAdvice class that extends ResponseEntityExceptionHandler should catch exceptions and provide the appropriate response.

Actual Behavior

•	The @ControllerAdvice is ignored, and exceptions are not caught by the custom exception handler.

Suspected Cause

•	The ModuleEntryInterceptor from spring-modulith-observability appears to intercept the method invocation and disrupt exception propagation.
•	It does not properly propagate the exceptions back to Spring MVC’s error handling flow, potentially causing the issue.

Environment

•	Spring Boot Version: 3.3.x
•	Spring Modulith Observability Version: 1.2.4
•	Java Version: 21

[odrotbohm]

This seems to duplicate GH-933 as ResponseEntityExceptionHandler implements an interface. Thus, a JDK proxy is created and the annotations on the actual class are not visible anymore. As a workaround, would you mind not making the class public? If a type is not part of a module's API it is not decorated anyway, and I'd argue that a REEH doesn't need to be a type exposed by a module.

For future reference, it would be appreciated if you provided a minimal reproducer instead of instructions on how to create a sample.