RFR: Merge jdk20

Tue Jan 24 21:46:12 UTC 2023

Forwardport JDK 20 -> JDK 21

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Commit messages:
 - Merge
 - 8300591: @SuppressWarnings option "lossy-conversions" missing from jdk.compiler module javadoc
 - 8300623: Lambda deserialization regression involving Enum method reference

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

Changes: https://git.openjdk.org/jdk/pull/12172/files
  Stats: 376 lines in 6 files changed: 47 ins; 325 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/12172.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12172/head:pull/12172

PR: https://git.openjdk.org/jdk/pull/12172