<i18n dev> RFR: 8366178: Implement JEP 526: Lazy Constants (Second Preview)

[Per Minborg]

On Mon, 13 Oct 2025 13:17:37 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Implement JEP 526: Lazy Constants (Second Preview)
>> 
>> The lazy list/map implementations are broken out from `ImmutableCollections` to a separate class.
>> 
>> The old benchmarks are not moved/renamed to allow comparison with previous releases.
>> 
>> `java.util.Optional` is updated so that its field is annotated with `@Stable`.  This is to allow `Optional` instances to be held in lazy constants and still provide constant folding.
>
> src/java.base/share/classes/java/util/LazyCollections.java line 360:
> 
>> 358: 
>> 359:         @Stable
>> 360:         private final Set<K> keySet;
> 
> I believe putting the field in here might cause some redundancies -- for instance LazyMap extends this class and addss a `Map<K, Integer>`, from which you can clearly derive the key set...

It is true that `AbstractMap` already contains a `keySet` field. If we annotate `AbstractMap.keySet` with `@Stable` (which seems ok to do), we can get rid of this field. A note here is that eventually, we would like to get rid of all the fields in `AbstractMap`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27605#discussion_r2426399337