RFR: Merge jdk20

[Jesper Wilhelmsson]

Forwardport JDK 20 -> JDK 21

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Commit messages:
 - Merge remote-tracking branch 'jdk20/master' into Merge_jdk20
 - 8300269: The selected item in an editable JComboBox with titled border is not visible in Aqua LAF

The merge commit only contains trivial merges, so no merge-specific webrevs have been generated.

Changes: https://git.openjdk.org/jdk/pull/12299/files
  Stats: 184 lines in 2 files changed: 183 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12299.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12299/head:pull/12299

PR: https://git.openjdk.org/jdk/pull/12299