code: @Action(
              semantics = SemanticsOf.SAFE
      )
      @ActionLayout(
              bookmarking = BookmarkPolicy.AS_ROOT
      )
      @MemberOrder(sequence = "1")
      public List<FullCalendar2WicketToDoItem> notYetComplete() {
          final List<FullCalendar2WicketToDoItem> items = notYetCompleteNoUi();
          if(items.isEmpty()) {
              container.informUser("All to-do items have been completed :-)");
          }
          return items;
      }
docs: region > notYetComplete (action)