[lworld] RFR: 8346307: [lworld] Clarify identity vs value in Class, Objects, and document limitations of value objects [v4]

[Joseph Tarbit]

On Tue, 4 Feb 2025 20:59:39 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> Add APINote  and javadoc for IdentityException where it will be useful to know that identity or value objects are treated differently. 
>> Simplified WeakHashMap javadoc updates for IdentityException. 
>> Added note to System.identityHashCode to include value objects.
>> Added to class javadoc for IdentityHashMap for value objects.
>
> Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Expand javadoc reference to Reference

src/java.base/share/classes/java/lang/Class.java line 713:

> 711:     @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective=true)
> 712:     public boolean isValue() {
> 713:         return PreviewFeatures.isEnabled() ? !isIdentity() : false;

Is there a reason this isn't just `PreviewFeatures.isEnabled() && !isIdentity()`?

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1327#discussion_r1957317190