@NotNull
  public static FrameDiffTool.DiffViewer createViewer(@NotNull DiffContext context,
                                                      @NotNull DiffElement element1,
                                                      @NotNull DiffElement element2,
                                                      @NotNull DirDiffSettings settings,
                                                      @Nullable String helpID) {
    return new DirDiffViewer(context, element1, element2, settings, helpID);
  }
@NotNull
  public static FrameDiffTool.DiffViewer createViewer(@NotNull DiffContext context,
                                                      @NotNull DiffElement element1,
                                                      @NotNull DiffElement element2,
                                                      @NotNull DirDiffSettings settings,
                                                      @Nullable String helpID)