package test;

import java.util.ArrayList;
import java.util.List;

public class Test {
    public static void main(String[] args)  {
        ParentB p = new ParentB();
        p.Children = new ArrayList<ChildB>();

        DoSmth(p);
    }

    static void DoSmth(Parent<ChildA> parent)
    {
        for (ChildA ch : parent.Children) {
            ch.Test();
        }
    }

}

class Child {}

class ChildA extends Child {
    public void Test() {
        System.out.println(1);
    }
}

class Parent<T extends Child> {
    public List<T> Children;
}

class ChildB extends ChildA {}

class ParentA extends Parent<ChildA> {}

class ParentB extends Parent<ChildB> {}