class RangeIndex extends MultiValueIndex {

  protected List<Object> higher(NavigableMap<Object, Set<Object>> map,
      Entry<Object, Set<Object>> current) {
    Set<Object> resultSet = new HashSet<Object>();
    while (current != null) {
      synchronized (current) {
        resultSet.addAll(current.getValue());
        current = map.higherEntry(current.getKey());
      }
    }
    return new ArrayList<Object>(resultSet);
  }

  public  RangeIndex();

}