protected static @NotNull List<Pair<Element, String>> splitState(@NotNull Element state, @NotNull String attributeName) {
    UniqueNameGenerator generator = new UniqueNameGenerator();
    List<Pair<Element, String>> result = new SmartList<>();
    for (Element subState : state.getChildren()) {
      if (subState.getAttribute(SerializationConstants.EXTERNAL_SYSTEM_ID_ATTRIBUTE) == null) {
        result.add(createItem(subState.getAttributeValue(attributeName), generator, subState));
      }
    }
    return result;
  }
protected static @NotNull List<Pair<Element, String>> splitState(@NotNull Element state, @NotNull String attributeName)