code: private RegistryAuth authWithCredentialHelper(final String credsStore,
                                                  final String registry) throws IOException {
      final DockerCredentialHelperAuth dockerCredentialHelperAuth =
          DockerCredentialHelper.get(credsStore, registry);
      return dockerCredentialHelperAuth == null ? null : dockerCredentialHelperAuth.toRegistryAuth();
    }
docs: Obtain auth using a credential helper.
  @param credsStore The name of the credential helper
  @param registry The registry for which we need to obtain auth
  @return A RegistryAuth object with a username, password, and server.
  @throws IOException This method attempts to execute
  "docker-credential-" + credsStore + " get". If you don't have the
  proper credential helper installed and on your path, this
  will fail.