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

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

    DiffUtil.addActionBlock(group, viewerActions);

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

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

    return group;
  }
 @Nullable
 public <T> T getContextUserData(@NotNull Key<T> key) {
   return myContext.getUserData(key);
 }