Can not put a T in Map

private static final Map<String, ? extends TrackingInterface<TrackResponseObject>> map = new HashMap<>();
    static {
        map.put("dunzo", new DunzoShipment());
        map.put("self", new SelfShipment());
    }

public class DunzoShipment implements TrackingInterface<TrackResponseObject>,java.util.function.Supplier<TrackingInterface<TrackResponseObject>> { 
//body
}

while puting the object into map i am getting an error:

The method put(String, capture#1-of ? extends TrackingInterface) in the type Map<String,capture#1-of ? extends TrackingInterface> is not applicable for the arguments (String, DunzoShipment)

? extends TrackingInterface