RFR: 8348880: Replace ConcurrentMap with AtomicReferenceArray for ZoneOffset.MINUTES_15_CACHE [v2]

[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:

  from @liach

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23337/files
  - new: https://git.openjdk.org/jdk/pull/23337/files/2394c087..3ec3c64c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23337&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23337&range=00-01

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 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