docs: public static String getRelativeSubPath(String base, String path) {
  
          String result = null;
          base = CmsStringUtil.joinPaths(base, "/");
          path = CmsStringUtil.joinPaths(path, "/");
          if (path.startsWith(base)) {
              result = path.substring(base.length());
          }
          if (result != null) {
              if (result.endsWith("/")) {
                  result = result.substring(0, result.length() - 1);
              }
              if (!result.startsWith("/")) {
                  result = "/" + result;
              }
          }
          return result;
      }