reproducible in all-nbms-hydra-070410_6
regression since Griffin.

If user has selected checkbox to create diagram during applying design pattern, 
IllegalStateException will rise.

steps:
- create java-model uml project
- add class element in model and name it.
- invoke 'Apply Design Pattern' for class node
- from Pattern Selection step:
  select "GoF Design Patterns" from the Project list 
  select "Creational::Builder" from the Design pattern list
- click 'Next' 3 times.
- On the "Options" step select 'Create class diagram' checkbox.
- finish process.
you will get IllegalStateException