final Diagram diagram = Graphiti.getCreateService().createDiagram(DiagramTypeProvider.DIAGRAM_TYPE_ID, filename, true);

addedClass.eResource().getContents().add(diagram);

link(diagram, addedClass);

link(containerShape, addedClass);

protected Collection<Diagram> getDiagrams() {
Resource resource = getDiagram().eResource();
       
// does resource contain a diagram as root object?
final EList<EObject> contents = resource.getContents();
List<Diagram> diagramCollection = new ArrayList<Diagram>();
       
for (final EObject object : contents) {
     if (object instanceof Diagram) {
           diagramCollection.add((Diagram) object);
     }
}
      
return diagramCollection;
}