void readExternal(@NotNull Element element) {
    Set<String> knownTags = new HashSet<>();
    knownTags.add(CommonCodeStyleSettingsManager.COMMON_SETTINGS_TAG);
    knownTags.add(CodeStyleSettings.ADDITIONAL_INDENT_OPTIONS);
    knownTags.add("option");
    for (CustomCodeStyleSettings settings : getAllSettings()) {
      knownTags.addAll(settings.getKnownTagNames());
      settings.readExternal(element);
    }
    for (Element child : element.getChildren()) {
      String tag = child.getName();
      if (!knownTags.contains(tag)) {
        myUnknownCustomElements.put(tag, JDOMUtil.internElement(child));
      }
    }
  }
void readExternal(@NotNull Element element)