RFR: 8028351: JWS doesn't get authenticated when using kerberos auth proxy

[Weijun Wang]

Please take a look at

    http://cr.openjdk.java.net/~weijun/8028351/webrev.00/

The bug is

    https://bugs.openjdk.java.net/browse/JDK-8028351

Basically, we now treat no password provided as empty password, this 
leads to a useless (and failed) login and has some other serious issues, 
say, too many unsuccessful login blocks a user account.

Thanks
Max