```
public class People {
    class Family extends People {
    }
}

public class Together {
    private static ConcurrentMap<String, Collection<Family>> familyMap= new ConcurrentHashMap<String, Collection<Family>>();
    private static ConcurrentMap<String, ConcurrentMap<String, Collection<People>>> registry2 = new ConcurrentHashMap<String, ConcurrentMap<String, Collection<People>>>();

    static {
        registry2.put(Family.class.toString(), familyMap); 
    }
}

```

(I already tried changing the declaration of `registry2` to having `? extends People`

The error is:
`The method put(String, ConcurrentMap<String,Collection<People>>) in the type Map<String,ConcurrentMap<String,Collection<People>>> is not applicable for the arguments (String, ConcurrentMap<String,Collection<Family>>)`

How can I put `familyMap` into the `registry2` hashmap?