code: public static MenuItemTransitionBuilder transit(String id, @IdRes int menuId, @NonNull Toolbar toolbar) {
          return new MenuItemTransitionBuilder(id, menuId, toolbar);
      }
docs: Creates a builder for a specific Toolbar {@link MenuItem}.
  
  @param id Same as calling {@link Transition#setId(String)}, set an ID for debugging purpose.
  @param menuId The ID of the MenuItem to have transition effect created.
  @param toolbar
  @return