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
 - 8298784: JFR: Test chunk integrity
 - 8298215: gc/g1/TestVerifyGCType.java failed with "Missing expected verification pattern Verifying After GC for: Pause Young (Prepare Mixed): expected true, was false"
 - 4958969: ObjectOutputStream example leads to non-working code
 - 8298699: java/lang/reflect/IllegalArgumentsTest.java times out with slowdebug bits
 - 4512626: Non-editable JTextArea provides no visual indication of keyboard focus
 - 8277074: Qualified exported types show up in JavaDoc
 - 8298894: java/lang/Thread/virtual/stress/Skynet.java timed out and threw OutOfMemoryError
 - 8298987: ProblemList jdk/internal/vm/Continuation/Fuzz.java#default with ZGC on X64
 - 8298905: Test "java/awt/print/PrinterJob/ImagePrinting/PrintARGBImage.java" fails because the frames of instruction does not display
 - ... and 6 more: https://git.openjdk.org/jdk/compare/36de61c4...d70f5831

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.org/?repo=jdk&pr=11739&range=00.0
 - jdk20: https://webrevs.openjdk.org/?repo=jdk&pr=11739&range=00.1

Changes: https://git.openjdk.org/jdk/pull/11739/files
  Stats: 2286 lines in 125 files changed: 1286 ins; 609 del; 391 mod
  Patch: https://git.openjdk.org/jdk/pull/11739.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11739/head:pull/11739

PR: https://git.openjdk.org/jdk/pull/11739