[jdk21u-dev] RFR: 8334394: Race condition in Class::protectionDomain

[Goetz Lindenmaier]

I backport this for parity with 21.0.9-oracle

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Commit messages:
 - Backport c3226aaeb810521257e961be5763552c86ee5651

Changes: https://git.openjdk.org/jdk21u-dev/pull/1877/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1877&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8334394
  Stats: 109 lines in 2 files changed: 92 ins; 10 del; 7 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1877.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1877/head:pull/1877

PR: https://git.openjdk.org/jdk21u-dev/pull/1877