private void checkForEmptyAndDuplicatedNames(
      MyNode rootNode,
      String prefix,
      String title,
      Class<? extends NamedConfigurable> configurableClass,
      boolean recursively)
      throws ConfigurationException {
    final Set<String> names = new HashSet<String>();
    for (int i = 0; i < rootNode.getChildCount(); i++) {
      final MyNode node = (MyNode) rootNode.getChildAt(i);
      final NamedConfigurable scopeConfigurable = node.getConfigurable();

      if (configurableClass.isInstance(scopeConfigurable)) {
        final String name = scopeConfigurable.getDisplayName();
        if (name.trim().length() == 0) {
          selectNodeInTree(node);
          throw new ConfigurationException("Name should contain non-space characters");
        }
        if (names.contains(name)) {
          final NamedConfigurable selectedConfigurable = getSelectedConfigurable();
          if (selectedConfigurable == null
              || !Comparing.strEqual(selectedConfigurable.getDisplayName(), name)) {
            selectNodeInTree(node);
          }
          throw new ConfigurationException(
              CommonBundle.message("smth.already.exist.error.message", prefix, name), title);
        }
        names.add(name);
      }

      if (recursively) {
        checkForEmptyAndDuplicatedNames(node, prefix, title, configurableClass, true);
      }
    }
  }
 @NotNull
 public String getDisplayName() {
   final NamedConfigurable configurable = ((NamedConfigurable) getUserObject());
   LOG.assertTrue(configurable != null, "Tree was already disposed");
   return configurable.getDisplayName();
 }