/**
  * Create a bundle from an bundle of identifiers.
  *
  * @param identifierBundle the identifier bundle, not null
  * @return the identifier bundle with dates set to null, not null
  */
 public static IdentifierBundleWithDates of(IdentifierBundle identifierBundle) {
   ArgumentChecker.notNull(identifierBundle, "identifierBundle");
   Set<IdentifierWithDates> identifiers = new HashSet<IdentifierWithDates>();
   for (Identifier identifier : identifierBundle) {
     identifiers.add(IdentifierWithDates.of(identifier, null, null));
   }
   return new IdentifierBundleWithDates(identifiers);
 }