Struggling with Bean Validation within a JAX RS running in a Glassfish Container - rest

Question

I'm working on a simple Java EE Application, using Glassfish.
Everything runs fine, my Entity and Session Beans are working.
I also created some JAX RS Resources to invoke the Session Beans, which also works fine.
Now I'm struggling with Bean Validation.
Let's have a look at a little snippet:
#GET
#Path( "{portaluser}" )
#NotNull
public PortaluserResponse load( #PathParam( "portaluser" ) #NotBlank #Email final String strEmail )
{ ... some implementation ... }
My Jersey Application, which of course extends ResourceConfig looks like this:
public JerseyApplication()
{
packages( PortaluserService.class.getPackage().getName() );
register( JacksonFeature.class );
register( ValidationConfig.class);
property( ServerProperties.BV_SEND_ERROR_IN_RESPONSE, true );
}
In my pom.xml I included following dependency:
<dependency>
<groupId>org.glassfish.jersey.ext</groupId>
<artifactId>jersey-bean-validation</artifactId>
<version>2.9</version>
</dependency>
If I invoke the REST Service with nonsense data, the validation doesn't kick in.
Why is that? I expect to get a validation error.
I found a jersey-Sample which covers the bean validation stuff. My REST-Resource works within that project.
The only difference is, that jersey-Sample doesn't run in Glassfish, but in a Jetty.
Can it be that jersey bean validation doesn't work when running in a Java EE container?
Would appreciate some hints.