how understanding "super" generics java?

take following generics example

import java.util.list;
import java.util.arraylist;

public category genericstest {
    private list<animal> mylist;

    open stationary vacant main(string args[]) {
        new genericstest(new arraylist<animal>()).add(new dog());
    }

    open genericstest(list<animal> list) {
        mylist = list;
    }

    open vacant add(animal a) {
      mylist.add(a);
    }

    open interface animal {}
    open stationary category dog implements animal {}
    open stationary category cat implements animal {}
}

it works fine. nonetheless know, can't make with

new genericstest(new arraylist<dog>());

because, know, add(animal) illusory supplement cats. suggested proceed clarify problem, i.e. wildcarding does work either, because, yes, change each list<animal> list<? extends animal> nonetheless same problem: emanate genericstest list<cat> following supplement dogs.

so doubt is: there accessible proceed category once, following illusory animals? impetus should solve sincerely above mentioned problem.