private static final long serialVersionUID = 1999400043787454432L;
    private static final Logger log = LoggerFactory.getLogger(Kerb5Authenticator.class);
    private static final String DEFAULT_SERVICE = "cifs";

    private static final Set<ASN1ObjectIdentifier> PREFERRED_MECHS = new HashSet<>();

    private Subject subject = null;
    private String user = null;
    private String realm = null;