<i18n dev> RFR: 8307547: Support variant collations [v4]

[Alan Bateman]

On Thu, 11 May 2023 20:51:37 GMT, Naoto Sato <naoto at openjdk.org> wrote:

>> The fix to https://bugs.openjdk.org/browse/JDK-8306927 switched the default collation for Swedish to the modern one. In order to provide a means for users who need the old collation, this PR intends to make `Collator` recognize the `co` Unicode locale extension so that multiple implementations for a locale can be provided. I would also like reviews for the corresponding CSR.
>
> Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Added "reformed" tests

The update, and API note in Collator.getInstance(Locale), looks okay to me. I'm just wondering where a developer might go to get a definitive list, i.e. aside from this API note, how would they know that "-trad" or "-traditional" can be used to configure the ordering. Locale.forLanguageTag supports more than BCP 47 language tag strings so is this considered a private use language tag.

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PR Comment: https://git.openjdk.org/jdk/pull/13917#issuecomment-1545395782