public class CovarianceTest {

    public static void doSomething(MyList<Animal> animals) {
    }

    public static void doSomethingGeneric(MyList<? extends Animal> genericAnimals) {
    }

    public static void main(String[] args) {

        MyListImp<Animal> animals = new MyListImp<>();
        MyListImp<Dog> dogs = new MyListImp<>();
        CovarianceTest.doSomething(animals);
        // CovarianceTest.doSomething(dogs);
        CovarianceTest.doSomethingGeneric(dogs);
        CovarianceTest.doSomethingGeneric(animals);
    }
}