@NotNull
  protected DefaultActionGroup collectToolbarActions(@Nullable List<? extends AnAction> viewerActions) {
    DefaultActionGroup group = new DefaultActionGroup();

    List<AnAction> navigationActions = Arrays.asList(new MyPrevDifferenceAction(), new MyNextDifferenceAction());
    DiffUtil.addActionBlock(group, navigationActions);

    DiffUtil.addActionBlock(group, viewerActions);

    List<AnAction> requestContextActions = myRequest != null ? myRequest.getUserData(DiffUserDataKeys.CONTEXT_ACTIONS) : null;
    DiffUtil.addActionBlock(group, requestContextActions);

    List<AnAction> contextActions = myContext.getUserData(DiffUserDataKeys.CONTEXT_ACTIONS);
    DiffUtil.addActionBlock(group, contextActions);

    return group;
  }
@NotNull
  protected DefaultActionGroup collectToolbarActions(@Nullable List<? extends AnAction> viewerActions)