Why is there no parameter contra-variance for overriding?

Question

C++ and Java support return-type covariance when overriding methods.

Neither, however, support contra-variance in parameter types - instead, it translates to overl

Answer 1

class A {
    public void f(String s) {...}
    public void f(Integer i) {...}
}

class B extends A {
    public void f(Object o) {...} // Which A.f should this override?
}