Integrated: Merge jdk19

[David Holmes]

Forward port JDK 19 -> JDK 20

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Commit messages:
 - Merge remote-tracking branch 'jdk19/master' into Merge_jdk19
 - 8290562: ThreadMXBean.getThread{Cpu,User}Time fails with -XX:-VMContinuations

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.org/?repo=jdk&pr=9787&range=00.0
 - jdk19: https://webrevs.openjdk.org/?repo=jdk&pr=9787&range=00.1

Changes: https://git.openjdk.org/jdk/pull/9787/files
  Stats: 99 lines in 2 files changed: 78 ins; 0 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/9787.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9787/head:pull/9787

PR: https://git.openjdk.org/jdk/pull/9787