private void notifyIdentifiers(Map identifierEventsByIdentifierId) {
    for (Iterator iterator = identifierEventsByIdentifierId.entrySet().iterator();
        iterator.hasNext(); ) {
      Map.Entry entry = (Map.Entry) iterator.next();
      String identifierId = (String) entry.getKey();
      IdentifierEvent identifierEvent = (IdentifierEvent) entry.getValue();
      Identifier identifier = (Identifier) identifiersById.get(identifierId);

      if (identifier != null) {
        identifier.fireIdentifierChanged(identifierEvent);
      }
    }
  }