@Nullable
  protected JComponent createTitles() {
    List<JComponent> titles = DiffUtil.createTextTitles(this, myRequest, Arrays.asList(myEditor, myEditor));
    assert titles.size() == 2;

    titles = ContainerUtil.skipNulls(titles);
    if (titles.isEmpty()) return null;

    return DiffUtil.createStackedComponents(titles, DiffUtil.TITLE_GAP);
  }
@Nullable
  protected JComponent createTitles()