private boolean isDuplicated(String description) {
    if (myDuplicateDescriptions == null) {
      myDuplicateDescriptions = new HashSet<>();
      Set<String> filter = new HashSet<>();
      for (int i = 0; i < myModel.getSize(); i++) {
        String s = myConverter.apply(myModel.getElementAt(i)).getDescription();
        if (!filter.add(s)) myDuplicateDescriptions.add(s);
      }
    }

    return myDuplicateDescriptions.contains(description);
  }
private boolean isDuplicated(String description)