This looks like a bug in IBM JDK. When introspecting a generic parameter of a method using getAnnotatedParameterTypes, IBM JDK returns an instance of sun.reflect.annotation.AnnotatedTypeFactory$AnnotatedTypeBaseImpl instead of the correct sun.reflect.annotation.AnnotatedTypeFactory$AnnotatedParameterizedTypeImpl

Confirmed. However, I don't think that we are able to do much here. AFAIKT our code does the right thing and it is indeed a bug in the IBM JVM. Would be interesting to know whether they are aware of it, but I am not even sure where and how to report these type of things.