code: private boolean checkCOSCredentials(UnderFileSystemConfiguration conf) {
      return conf.isSet(PropertyKey.COS_ACCESS_KEY)
          && conf.isSet(PropertyKey.COS_SECRET_KEY)
          && conf.isSet(PropertyKey.COS_REGION);
    }
docs: @param conf optional configuration object for the UFS
  
  @return true if both access, secret and endpoint keys are present, false otherwise