[8u] RFR: 8256682: JDK-8202343 is incomplete

[Alexey Bakhtin]

Hi,
Please review the backport of JDK-8256682 to 8u:

Bug: https://bugs.openjdk.java.net/browse/JDK-8256682
Original change: https://github.com/openjdk/jdk/commit/b9db002f
8u webrev: http://cr.openjdk.java.net/~abakhtin/8256682/webrev.v0/

Original fix does not apply cleanly because of NullHostnameCheck.java test was not updated as part of JDK-8202343 8u backport [1]. This patch includes missed parts of the original fix for JDK-8202343 [2].

[1] https://hg.openjdk.java.net/jdk8u/jdk8u-dev/jdk/rev/f2f0ceec19fb
[2] https://github.com/openjdk/jdk/commit/3a4b90f0

Regards
Alexey