class GenericMethodArguments {

    static class Items<T> {
        public <Output extends T> Output apply(Transform<? super Items<T>, Output> t) {
            return null;
        }
    }

    static class Transforms {
        public static <I, O> Transform<I, O> of(DoFn<I, O> fn) {
            return null;
        }
    }

    static class Transform<Input, Output> {}

    static class DoFn<Input, Output> {}

    static class MyFn1<T> extends DoFn<T, Long> {}

    static class MyFn2 extends MyFn1<Integer> {}

    private Items<Integer> items;

    public void useCase1() {
        items.apply(Transforms.of(new MyFn2()));
    }

    public void useCase2() {
        items.apply(Transforms.of(new DoFn<Integer,Long>(){}));
    }

}