RFR: 8359119: Change Charset to use StableValue [v2]

[Per Minborg]

On Tue, 10 Jun 2025 15:04:44 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> Per Minborg has updated the pull request incrementally with three additional commits since the last revision:
>> 
>>  - Revert for loop
>>  - Revert more
>>  - Revert changes
>
> src/java.base/share/classes/java/nio/charset/Charset.java line 384:
> 
>> 382: 
>> 383:     private static final Supplier<ThreadTracker> TRACKER = StableValue.supplier(
>> 384:             new Supplier<>() { public ThreadTracker get() { return new ThreadTracker(); }});
> 
> ThreadTracker pre-dates ScopedValue. We could potentially use a  ScopedValue<Boolean> IN_USE here, or StableValue<ScopedValue<Boolean>> if there are issues running the class initializer in early VM startup. Separate discussion but we don't need ThreadTracker now.

So, revert the changes here?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25727#discussion_r2138177730