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

[Roger Riggs]

> 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

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Changes:
  - all: https://git.openjdk.org/valhalla/pull/1327/files
  - new: https://git.openjdk.org/valhalla/pull/1327/files/850923bd..d450add4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1327&range=03
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1327&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/1327.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1327/head:pull/1327

PR: https://git.openjdk.org/valhalla/pull/1327