Generics from interface method are stripped

Question

I have this interface:

public interface Persistant<T extends BaseDaoEnabled<T, UUID>> extends Identifiable {

T getSelf();

default <P> P getInstance(DataKey<P> key) {
    return key.getDefaultInstance();
}

and a class that implements it. My problem is that when I call obj.getInstance(DataKeys.X), X being a DataKey<X> object, the return type of this method is Object and not X, the generic type is stripped. When I put the method inside my object class (not interface), it works just fine. See the screenshot below:

First method is from the interface, 2nd method is from the class. They both have the SAME signature

Answer 1

The interface has a type parameter (Persistant<T...>) that I forgot to include on my Resident/obj class. I was implementing it by just using implements Persistant, implementing it using implements Persistant<Resident> fixed my issue!