class A<T extends A<T>> {
    class C {
        public T getT() { return null; }
    }
}

class B extends A<B> {
    public class D extends A<B>.C {}
}

class Test {
    void test(B.D d) {
        B b = d.getT();
    }
}

If all three classes are compiled at the same time, no error occurs. If, after having compiled all classes, only Test is recompiled, the following compiler error occurs:

TestX.java:14: incompatible types
        B b = d.getT();
                    ^
  required: B
  found: A
1 error