class KeySet implements Set<String> {

    @SuppressWarnings("unchecked")
    @Override
    public boolean containsAll(Collection<?> c) {
        Collection<String> realCollection = (Collection<String>) c;
        for (String key : realCollection) {
            if (request.getValue(key(key)) == null) {
                return false;
            }
        }
        return true;
    }

    public  KeySet(HasKeys<?> request);

}