the example below compiles successfully on JDK8b132, but it seems to me that it should fail according to spec.

    class Container<U> {
        U t;
    }

    interface Supertype<U> {
    }

    interface Type1 extends Supertype<Number> {
    }

    interface Type2 extends Supertype<Integer> {
    }

    public class Main {
        static <U extends Type1> void m(Container<? super U> a) {
        }

        public static void main(String[] args) {
            m(new Container<Type2>());
        }
    }