Generic Classes and Subtyping in Java

Generic Classes and Subtyping in Java.md

https://docs.oracle.com/javase/tutorial/java/generics/inheritance.html

interface PayloadList<E,P> extends List<E> {
    void setPayload(int index, P val);
}

class NewList implements PayloadList<Integer, String> {
  //...implement interface methods..
}

// Polymorphism
List<Integer> pl = new NewList(); // is valid
List<String> pl = new NewList();  // is invalid