public ErrorTreeElement addSimpleMessageElement(ErrorTreeElement element) {
    synchronized (myLock) {
      List<ErrorTreeElement> elements = mySimpleMessages.get(element.getKind());
      if (elements == null) {
        elements = new ArrayList<>();
        mySimpleMessages.put(element.getKind(), elements);
      }
      elements.add(element);
    }
    return element;
  }
public ErrorTreeElement addSimpleMessageElement(ErrorTreeElement element)