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