code: public static String getImageLink(String imagePath) {
  
          return CmsStringUtil.joinPaths(
              OpenCms.getSystemInfo().getContextPath(),
              "VAADIN/themes/opencms/img-extra",
              imagePath);
      }
docs: Gets the link to an image below the img-extra folder.<p>
  
  @param imagePath the image path below img-extra
  
  @return the complete image link