gistfile1.java

    class A {}
    class B extends A {}

    class Foo<X extends A> {
        //fails
        void foo(X x, Predicate<X> p) {
            if (x instanceof B) {
                p.apply((B) x);
            }
        }
        //works
        void foo2(X x, Predicate<X> p) {
            if (x instanceof B) {
                B b = (B) x;
                p.apply((X) b);
            }
        }
        //works
        void foo3(X x, Predicate<A> p) {
            if (x instanceof B) {
                p.apply((B) x);
            }
        }
    }