@Specializes is not working if extended class is abstract

When @Specializes an abstract class, specialization fails mit following exception:

org.apache.webbeans.exception.WebBeansDeploymentException: org.apache.webbeans.exception.inject.InconsistentSpecializationException: WebBean component class : de.orbitx.specializes.ConcreteFooProducer is not enabled for specialized by the class de.orbitx.specializes.ConcreteFooProducer class
at org.apache.webbeans.config.BeansDeployer.checkSpecializations(BeansDeployer.java:709)
at org.apache.webbeans.config.BeansDeployer.deploy(BeansDeployer.java:188)
at org.apache.openejb.cdi.OpenEJBLifecycle.startApplication(OpenEJBLifecycle.java:182)
at org.apache.openejb.cdi.ThreadSingletonServiceImpl.initialize(ThreadSingletonServiceImpl.java:158)
at org.apache.openejb.cdi.CdiBuilder.build(CdiBuilder.java:43)
at org.apache.openejb.assembler.classic.Assembler.createApplication(Assembler.java:798)
at org.apache.openejb.assembler.classic.Assembler.createApplication(Assembler.java:612)
at org.apache.openejb.assembler.classic.Assembler.createApplication(Assembler.java:608)
at org.apache.openejb.testing.ApplicationComposers.before(ApplicationComposers.java:580)
at org.apache.openejb.testing.ApplicationComposers.evaluate(ApplicationComposers.java:664)
at org.apache.openejb.junit.ApplicationComposer$DeployApplication.evaluate(ApplicationComposer.java:64)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: org.apache.webbeans.exception.inject.InconsistentSpecializationException: WebBean component class : de.orbitx.specializes.ConcreteFooProducer is not enabled for specialized by the class de.orbitx.specializes.ConcreteFooProducer class
at org.apache.webbeans.util.WebBeansUtil.configureSpecializations(WebBeansUtil.java:784)
at org.apache.webbeans.util.WebBeansUtil.configureSpecializations(WebBeansUtil.java:643)
at org.apache.webbeans.config.BeansDeployer.checkSpecializations(BeansDeployer.java:700)
... 25 more

Please see the attached replication example (testcase: FooTest).

kind regards
Reinis