Yes and no. Java interfaces are a very degenerate case of roles. They provide no default behavior (a few constants notwithstanding), they are special cases in

Yes and no. Java interfaces are a very degenerate case of roles. They provide no default behavior (a few constants notwithstanding), they are special cases in at least part of the type system (declaring a class does not also declare a role), and I know of no good way to handle conflicts when implementing multiple interfaces with overlapping requirements.