code: public String getCaption() {
          if (item.captionCode().isEmpty()) {
              return item.caption();
          } else {
              return i18n.get(item.captionCode());
          }
      }
docs: Returns the caption of this side bar item. If the caption was specified using {@link org.vaadin.spring.sidebar.annotation.SideBarItem#captionCode()},
  this method will fetch the string from {@link org.vaadin.spring.i18n.I18N}.
  
  @return a string, never {@code null}.