Fix #398: Add portable ConstraintViolationExceptionMapper for MVC validation on OpenLiberty

[ivargrimstad]

Summary

Fixes #398

On OpenLiberty (and other JAX-RS runtimes that don't have a Krazo-specific mechanism to suppress built-in bean validation), the JAX-RS runtime validates controller method parameters and throws ConstraintViolationException before Krazo's CDI ValidationInterceptor can run. This results in a 400 Bad Request response instead of populating BindingResult and invoking the controller.

Jersey and RESTEasy have runtime-specific hooks (KrazoValidationInterceptor and KrazoGeneralValidator) that suppress this premature validation, but there was no equivalent for OpenLiberty/CXF.

Solution

This PR adds a portable ExceptionMapper<ConstraintViolationException> in the core module that:

1. Detects MVC controller requests via ResourceInfo and @Controller annotation
2. Populates BindingResult with @MvcBinding-annotated constraint violations (reusing the same logic as ValidationInterceptor)
3. Invokes the controller method via CDI so the controller can check BindingResult.isFailed() and return the appropriate view
4. Skips re-validation in the CDI ValidationInterceptor via a validationPerformedExternally flag on BindingResultImpl
5. Returns the controller's response with a Viewable entity for view rendering, or handles redirects

For non-MVC requests, the mapper returns a standard 400 Bad Request response (same as the default JAX-RS behavior).

Files Changed

• ConstraintViolationExceptionMapper.java (new) — The core ExceptionMapper
• BindingResultImpl.java — Added validationPerformedExternally flag
• ValidationInterceptor.java — Skips validation when flag is set
• DefaultConfigProvider.java — Registers the new ExceptionMapper

Limitations

• The controller method is invoked with default parameter values (nulls/zeros) since the original JAX-RS-bound values aren't accessible from the ExceptionMapper. Controllers should check BindingResult.isFailed() before using parameter values, which is the expected MVC pattern.
• This mapper is a safety net — on Jersey and RESTEasy, the existing runtime-specific interceptors prevent the exception from being thrown in the first place.

[mthmulders]

@ivargrimstad Would you like me to try and build this branch locally to see if it works?

Yes, that would be awesome!

I must admit I let GitHub CoPilot do all the work and I just haven't had time to test it yet since I am a little busy at OCX this week.

[mthmulders]

Tried building locally but ran into this error:

[ERROR] 'dependencies.dependency.version' for org.jboss.shrinkwrap.resolver:shrinkwrap-resolver-depchain:pom is missing. @ line 57, column 21

I see Jenkins failed with the same error. @ivargrimstad, does that make any bell ring, maybe?

Update: as a work-around, I set tck.version in the project root POM to "3.0.0".

[mthmulders]

I've tried it on the attached reproducer project. The ConstraintViolationExceptionMapper gets invoked at the expected moment. However, it fails to invoke the MVC controller because of an ResteasyViolationExceptionImpl that happens at line 138 (at CdiUtils.newBean(CdiUtils.getApplicationBeanManager(), resourceClass)).

Here is the full stack trace:

 	at org.jboss.resteasy.plugins.validation.GeneralValidatorImpl.checkViolationsfromCDI(GeneralValidatorImpl.java:172)
 	at [internal classes]
 	at org.jboss.weld.bean.ManagedBean.create(ManagedBean.java:161)
 	at org.jboss.weld.contexts.unbound.DependentContextImpl.get(DependentContextImpl.java:64)
 	at org.jboss.weld.bean.ContextualInstanceStrategy$DefaultContextualInstanceStrategy.get(ContextualInstanceStrategy.java:100)
 	at org.jboss.weld.bean.ContextualInstance.get(ContextualInstance.java:50)
 	at org.jboss.weld.manager.BeanManagerImpl.getReference(BeanManagerImpl.java:679)
 	at org.jboss.weld.manager.BeanManagerImpl.getReference(BeanManagerImpl.java:702)
 	at org.eclipse.krazo.util.CdiUtils.newBean(CdiUtils.java:72)
 	at org.eclipse.krazo.binding.ConstraintViolationExceptionMapper.handleMvcController(ConstraintViolationExceptionMapper.java:138)
 	at org.eclipse.krazo.binding.ConstraintViolationExceptionMapper.toResponse(ConstraintViolationExceptionMapper.java:95)
 	at org.eclipse.krazo.binding.ConstraintViolationExceptionMapper.toResponse(ConstraintViolationExceptionMapper.java:60)
 	at org.jboss.resteasy.core.ExceptionHandler.executeExceptionMapper(ExceptionHandler.java:139)
 	at [internal classes]
 	at org.jboss.resteasy.core.SynchronousDispatcher.lambda$invoke$4(SynchronousDispatcher.java:240)
 	at org.jboss.resteasy.core.SynchronousDispatcher.lambda$preprocess$0(SynchronousDispatcher.java:154)
 	at org.jboss.resteasy.core.interception.jaxrs.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:385)
 	at [internal classes]
 	at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:614)
 	at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1262)
 	at [internal classes]
 	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1090)
 	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:614)
 	at java.base/java.lang.Thread.run(Thread.java:1516)