RFR: 8348880: Replace ConcurrentMap with AtomicReferenceArray for ZoneOffset.MINUTES_15_CACHE [v4]

[Shaojin Wen]

> ZoneOffset.MINUTES_15_CACHE uses AtomicReferenceArray to replace ConcurrentMap to avoid object allocation caused by boxing from int to Integer during access.

Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:

  Update src/java.base/share/classes/java/time/ZoneOffset.java
  
  Co-authored-by: Chen Liang <liach at openjdk.org>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23337/files
  - new: https://git.openjdk.org/jdk/pull/23337/files/2402d5c8..12f27a62

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23337&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23337&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23337.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23337/head:pull/23337

PR: https://git.openjdk.org/jdk/pull/23337