code: private String extractGroup(String path) {
          if (TextUtils.isEmpty(path) || !path.startsWith("/")) {
              throw new HandlerException(Consts.TAG + "Extract the default group failed, the path must be start with '/' and contain more than 2 '/'!");
          }
  
          try {
              String defaultGroup = path.substring(1, path.indexOf("/", 1));
              if (TextUtils.isEmpty(defaultGroup)) {
                  throw new HandlerException(Consts.TAG + "Extract the default group failed! There's nothing between 2 '/'!");
              } else {
                  return defaultGroup;
              }
          } catch (Exception e) {
              logger.warning(Consts.TAG, "Failed to extract default group! " + e.getMessage());
              return null;
          }
      }
docs: Extract the default group from path.