For the Movie class, you specified default values using a display group. This approach is also the more appropriate choice for the MovieRole class, but you'll use the other approach for MovieRole just to see how its done.
public void awakeFromInsertion(EOEditingContext context){ super.awakeFromInsertion(context); roleName = "New Role"; }
This method is automatically invoked right after your enterprise object class creates a new MovieRole and inserts it into an editing context, which happens when you use a display group to insert.