private void calcDuplicates() {
    if (duplicateNames == null) {
      duplicateNames = new HashSet<>();
      Set<String> usedNames = new HashSet<>();
      for (String model : fileChooser.getMarkedElements()) {
        final String projectName = EclipseProjectFinder.findProjectName(model);
        if (!usedNames.add(projectName)) {
          duplicateNames.add(projectName);
        }
      }
    }
  }
private void calcDuplicates()