code: public static boolean checkUri(String uri) {
          QueryStringDecoder queryStringDecoder = new QueryStringDecoder(uri, true);
          String path = queryStringDecoder.path();
          int groupIndex = path.indexOf('/') + 1,
                  unitIndex = path.indexOf('/', groupIndex) + 1;
          if (groupIndex == 0 || unitIndex == 0) {
              LOG.warn("URI is illegal: " + uri);
              return false;
          }
          return true;
      }
docs: Check the uri is xian pattern or not.
  xian pattern uri must starts with /${group}/${unit}
  TODO combine URI checking with UriBean creation. And use UriBean reference instead of URI string later on for performance consideration.
  
  @param uri the URI to be checked
  @return true if it is xian pattern false other wise.