/**
  * Checks if this bundle contains any key from the specified bundle.
  *
  * @param bundle the bundle to search for, not null
  * @return true if this bundle contains any key from the specified bundle
  */
 public boolean containsAny(IdentifierBundleWithDates bundle) {
   ArgumentChecker.notNull(bundle, "bundle");
   for (IdentifierWithDates identifier : bundle.getIdentifiers()) {
     if (_identifiers.contains(identifier)) {
       return true;
     }
   }
   return false;
 }
 // -------------------------------------------------------------------
 @Override
 public int compareTo(IdentifierBundleWithDates other) {
   final Set<IdentifierWithDates> mySet = getIdentifiers();
   final Set<IdentifierWithDates> otherSet = other.getIdentifiers();
   if (mySet.size() < otherSet.size()) {
     return -1;
   }
   if (mySet.size() > otherSet.size()) {
     return 1;
   }
   final List<IdentifierWithDates> myList =
       new ArrayList<IdentifierWithDates>(mySet); // already sorted as TreeSet
   final List<IdentifierWithDates> otherList =
       new ArrayList<IdentifierWithDates>(otherSet); // already sorted as TreeSet
   for (int i = 0; i < myList.size(); i++) {
     int c = myList.get(i).compareTo(otherList.get(i));
     if (c != 0) {
       return c;
     }
   }
   return 0;
 }