This PR corrects the special case handling in `Locale.Builder.setLocale`. The
current handling always assumes a `Locale` matching the `ja/JP/JP` and
`th/TH/TH` special cases will contain the correct compatibility extensions. A
user can remove the extension or create a Locale in the form of the special
case without the correct compatibility extension.
For example, the current implementation does the following,
> jshell> loc = new Builder().setLocale(Locale.of("ja", "JP",
> "JP").stripExtensions()).build()
> loc ==> ja_JP
>
> jshell> loc = new
> Builder().setLocale(Locale.forLanguageTag("ja-JP-u-ca-foobar-x-lvariant-JP")).build()
> loc ==> ja_JP_#u-ca-foobar
That is, it silently discards the ill-formed JP variant.
With assertions on, this instead becomes a `NullPointerException` when the
extensions are not present, or an `AssertionError` when the extension has the
wrong value.
For the example above, one would expect an `IllFormedLocaleException` to be
thrown, since without a correct compatibility extension, JP is merely an
invalid variant and `setLocale(Locale)` throws on ill-formed fields.
The changes in this PR ensure that these cases throw as expected.
---------
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Interim AI Policy](https://openjdk.org/legal/ai).
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Commit messages:
- Add test case for incorrect extension value
- init
Changes: https://git.openjdk.org/jdk/pull/31728/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=31728&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8387455
Stats: 26 lines in 2 files changed: 16 ins; 0 del; 10 mod
Patch: https://git.openjdk.org/jdk/pull/31728.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/31728/head:pull/31728
PR: https://git.openjdk.org/jdk/pull/31728
