RFR: 8194676 NullPointerException is thrown if ipaddress is not set

[vyom tewari]

Hi,

Please review below code change for simple fix.
Webrev: http://cr.openjdk.java.net/~vtewari/8194676/webrev0.0/index.html

BudID: https://bugs.openjdk.java.net/browse/JDK-8194676

The code change will fix the unintentional NullPointerException. If ip 
address is not set, while de-serialization NPE will be thrown.

After the change the "readObject" will throw "InvalidObjectException" 
which is already thrown when code will check for "ipaddress.length" 
invariant.

Thanks,

Vyom