RFR: 8282511: Use fixed certificate validation date in SSLExampleCert template [v2]

[Xue-Lei Andrew Fan]

> May I have this test update reviewed?
> 
> The certificates used in SSL testing template SSLExampleCert could expired in the future (for example [JDK-8282398](https://bugs.openjdk.java.net/browse/JDK-8282398)).  It is not always easy to replace the certificates if the template has been used a lot.
> 
> This update is trying to use a fixed validation date, so that even the certificates are expired the test will continue to work with no surprises.
> 
> I also did a few code clean up in this patch.

Xue-Lei Andrew Fan has updated the pull request incrementally with one additional commit since the last revision:

  Chaneg to use DateFormat

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7651/files
  - new: https://git.openjdk.java.net/jdk/pull/7651/files/2352eea5..64c60b39

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7651&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7651&range=00-01

  Stats: 5 lines in 2 files changed: 2 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7651.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7651/head:pull/7651

PR: https://git.openjdk.java.net/jdk/pull/7651