The following cast is safe yet we give a warning:

class X {
    interface CF<S> { }
    interface CG<T> { }
    static class CH<S, T> implements CF<S>, CG<T> { }
    interface CI<S> extends CF<S> { }
    interface CJ<T> extends CG<T> { }
    interface CK<S, T> extends CI<S>, CJ<T> { }
    void f() {
        Object o = (CH<String, Integer>) (CK<String, Integer>) null; // <<pass>> <<todo: cast-infer>>
    }
}