RFR: 8351565: Implement JEP 502: Stable Values (Preview) [v25]

[Per Minborg]

On Wed, 2 Apr 2025 09:34:57 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Per Minborg has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Add lazy toSting for StableMap::values
>>  - Make toString for reversed and sublist lazy
>
> src/java.base/share/classes/java/lang/StableValue.java line 657:
> 
>> 655:      * @param <V>    the type of mapped values in the returned map
>> 656:      */
>> 657:     static <K, V> Map<K, V> map(Set<K> keys,
> 
> Like `List`, a map can also generate other kinds of collections:
> 1. an entry set (`Map::entrySet`)
> 2. a key set (`Map::keySet`)
> 3. a value set (`Map::values`)
> 
> We should make it clear that calling (1) and (3) will result in materializing the values for the map -- we do not have "lazy" views for such sets.

These constructs are also lazy actually which is cool. Operating on them will only materialize values on demand.

We should document that.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23972#discussion_r2024806772