Yes, the point is, the code to make it conform is independent on both A and B. So no need to modify either library. And sure, we can discuss what OOP is, but I

Yes, the point is, the code to make it conform is independent on both A and B. So no need to modify either library. And sure, we can discuss what OOP is, but I am using the most widely used definition of classes and interfaces, as understood by Java and .NET.