hello Necesito implementar un método que reciba un HashMap y clasifique (mergeSort) sus valores por clave (sin usar TreeMap, SortedMap o Collections.Sort o usar cualquier solución de clasificación de los paquetes JAVA). mi problema es tratar con los tipos de comodines ... esta es mi implementación (que devuelve errores de compilación debido al uso de comodines)

public HashMap<?, ?> mergeSort(HashMap<?, ?> map) {
        if (map.size() < 1) {
            return map;
        }
        // rounds downwards
        int middle = map.size() / 2;
        int location = 0;

        HashMap<?,?> mapLeft = new HashMap<?, ?>();
        HashMap<?,?> mapRight = new HashMap<?, ?>();
        // splitting map
        for (Iterator<?> keyIter = map.keySet().iterator(); keyIter.hasNext();) {
            if (location < middle) {
                mapLeft.put(keyIter, map.get(keyIter));
            } else {
                mapRight.put(keyIter, map.get(keyIter));
            }
            location++;
        }
        // recursive call
        mapLeft = mergeSort(mapLeft);
        mapRight = mergeSort(mapRight);
        return merge(mapLeft, mapRight);
    }

    public HashMap<?, ?> merge(HashMap<?, ?> mapLeft, HashMap<?, ?> mapRight) {
        HashMap<?, ?> result = new HashMap<?, ?>();
        Iterator<?> keyLeftIter = mapLeft.keySet().iterator();
        Iterator<?> keyRightIter = mapRight.keySet().iterator();
        String keyLeft;
        String keyRight;
        while (keyLeftIter.hasNext()) {
            keyLeft = keyLeftIter.next();
            while (keyRightIter.hasNext()) {
                keyRight = keyRightIter.next();

                if (keyLeft.compareTo(keyRight) < 0) {
                    result.put(keyLeft, mapLeft.get(keyLeft));
                    keyLeft = keyLeftIter.next();
                } else {
                    result.put(keyRight, mapRight.get(keyRight));
                    keyRight = keyRightIter.next();
                }
            }
        }
        return result;
    }

¡Aprecio tu ayuda