private boolean add(Map map, ClassDoc superclass, ClassDoc cd) {
        List list = (List)map.get(superclass);
        if (list == null) {
            list = new ArrayList();
            map.put(superclass, list);
        }
        if (list.contains(cd)) {
            return false;
        } else {
            list.add(cd);
        }
        return true;
    }