class CaselessUnmodifiableMultivaluedMap extends CaselessMultivaluedMap<T> {

    @Override
    public Set<String> keySet() {
        if (keys == null) {
            keys = new ReadOnlyKeySet();
        }
        return keys;
    }

    public  CaselessUnmodifiableMultivaluedMap();
    public  CaselessUnmodifiableMultivaluedMap(int capacity);
    public  CaselessUnmodifiableMultivaluedMap(Map<String, List<T>> m);

}