[11u] RFR: 8212970: TZ database in "vanguard" format support

[Martin Buchholz]

(not a review)
At Google, we decided to stay on rearguard format tzdata files for all our
jdks.
One reason for that was being able to easily support older jdk versions
with the same data files.
Vanguard still seems riskier to me than rearguard.
Of course, eventually we'll need to switch to vanguard, and this backport
will make that possible earlier.

Another pitfall when backporting to jdk8 is that there are two copies of
all the tzdata files in the repo.

On Wed, Sep 18, 2019 at 2:46 AM Langer, Christoph <christoph.langer at sap.com>
wrote:

> Hi,
>
> please review this backport to JDK11 updates:
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8212970
> Webrev: http://cr.openjdk.java.net/~clanger/webrevs/8212970.11u-dev.0/
> Original Change: https://hg.openjdk.java.net/jdk/jdk/rev/99d2dd7b84a8
>
> This backport is prerequisite to JDK-8228469: (tz) Upgrade time-zone data
> to tzdata2019b, which is required for 11.0.5. This will make the JDK's
> timezone parser support the "vanguard" format and enables a simple backport
> of JDK-8228469.
>
> To make the patch applicable to jdk11u, I had to manually do all the
> deletions in  test/jdk/sun/util/calendar/zi/tzdata and
> test/jdk/sun/util/calendar/zi/tzdata_jdk.
>
> Furthermore there were some rejects which were easy to resolve in:
> make/jdk/src/classes/build/tools/tzdb/TzdbZoneRulesCompiler.java ->
> Copyright year
> make/jdk/src/classes/build/tools/tzdb/TzdbZoneRulesProvider.java ->
> Copyright year and import statements
> src/java.base/share/classes/java/time/zone/Ser.java -> Copyright year
> src/java.base/share/classes/java/time/zone/ZoneOffsetTransitionRule.java
> -> Copyright year
>
> With the patch applied all regression testing shows still green (both,
> jtreg and TCK).
>
> Thanks
> Christoph
>
>