Gonçalo Marques created OPENEJB-2125:
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Summary: CDI extension that wraps an InjectionTarget (JAX-RS)
causes a ClassCastException
Key: OPENEJB-2125
URL: https://issues.apache.org/jira/browse/OPENEJB-2125
Project: OpenEJB
Issue Type: Bug
Components: integration, tomee
Affects Versions: (not version related)
Reporter: Gonçalo Marques
If an arbitrary CDI extension wraps a {{InjectionTarget}} during {{@Observes
ProcessInjectionTarget<T>}} event, it will result in a {{ClassCastException}}
in TomEE JAX-RS service startup.
*Example*
{code:borderStyle=solid}
// InjectionTarget wrapper
public class InjectionTargetWrapper<T> implements InjectionTarget<T>
{
private final InjectionTarget<T> wrapped;
public InjectionTargetWrapper(InjectionTarget<T> injectionTarget){
this.wrapped = injectionTarget;
}
// All InjectionTarget interface methods
// delegate to the wrapped instance and
// decorate the wrapped instance
// implementation where needed
}
// CDI extension
public class SomeExtension implements Extension {
<T> void processInjectionTarget(@Observes ProcessInjectionTarget<T> pit,
BeanManager beanManager) {
InjectionTarget<T> it = pit.getInjectionTarget();
pit.setInjectionTarget(new InjectionTargetWrapper<T>(it);
}
}
{code}
With the aforementioned wrapping, any existing CDI managed JAX-RS endpoint that
is processed by the CDI extension will have its {{InjectionTarget}} changed to
the wrapper type: {{InjectionTargetWrapper}}.
This results in a {{ClassCastException}} during TomEE JAX-RS service startup,
more precisely in
{{org.apache.openejb.server.cxf.rs.CdiResourceProvider#findContexts(final
Class<?> clazz)}}.
This method will be called by the CXF application deployment while processing
the JAX-RS endpoint bean and will cast the bean {{InjectionTarget}} to
{{InjectionTargetImpl}}. Since the JAX-RS bean {{InjectionTarget}} has been
changed to the wrapper - of type {{InjectionTargetWrapper}} - this results in a
{{ClassCastException}}.
This has been originally reported [at
GitHub|https://github.com/gonmarques/cdi-properties/issues/2]. The specific CDI
extension class may also be found at GitHub
[com.byteslounge.cdi.extension.PropertyExtension|https://github.com/gonmarques/cdi-properties/blob/master/cdi-properties-main/src/main/java/com/byteslounge/cdi/extension/PropertyExtension.java].
While the just mentioned extension is more complex than the initial example
described in this issue, this problem will occur for every CDI extension that
happens to process and change a JAX-RS endpoint {{InjectionTarget}} to another
type, ex: a wrapper (if the wrapper itself does not inherit from OpenWebBeans
{{InjectionTargetImpl}} of course, but this is not likely to happen for the
obvious reasons).
I will attach a very simple ready-to-build project that demonstrates the issue.
The project has a JAX-RS endpoint and includes the aforementioned CDI
extension. The problem will immediately occur if the application is deployed in
TomEE JAX-RS v1.7.3
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