RFR: 8351565: Implement JEP 502: Stable Values (Preview)

[Per Minborg]

On Tue, 11 Mar 2025 08:44:51 GMT, Per Minborg <pminborg at openjdk.org> wrote:

>> What if instead you had a `@Stable` array of Object of the appropriate size, and populated each cell with a StableValue if the corresponding index was in the set, otherwise used a sentinel value. Then on the lookup, if it was the sentinel you throw, else you use the the SV.
>> 
>> Also there is an awful lot of similarity between the enum function and the int function. Could one possibly be implemented using the other?
>
> Thanks for spotting this glitch. I have fixed the issue and added a test for member sets with "holes".

It might be worth exploring using a stable int function.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23972#discussion_r1991590911