Hi,
This is what I'm trying to achieve:
...
 @Entity
 @IdClass(MyPKClass.class)
 public class MyClass {
 ...
 }
This is a fully javassist generated class, I am able to annotate with the @Entity, even add member values in form name=value... but how shall I proceed to add the member value to @IdClass? 
Tried this so far (with mv = new ClassMemberValue(MyPKClass.class.getName(), cp);): 
- annotation.addMemberValue( "", mv ); 
- annotation.addMemberValue( null, mv ); 
- annotation.addMemberValue( -1, mv ); 
- annotation.addMemberValue( 0, mv ); 
Even tried to add annotation with param itself, wich didn't worked obviously: 
new Annotation("javax.persistence.IdClass(MyPKClass.class)", cp); 
Obviously I'm on the desperate side, trying desperate solutions... Any help ? 
Thanks & BR 
Alexandre Mendonca