[jdk20u] RFR: 8304671: javac regression: Compilation with --release 8 fails on underscore in enum identifiers

[Matthias Baesken]

8304671: javac regression: Compilation with --release 8 fails on underscore in enum identifiers

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Commit messages:
 - Backport 63d4afbeb17df4eff0f65041926373ee62a8a33a

Changes: https://git.openjdk.org/jdk20u/pull/23/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk20u&pr=23&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304671
  Stats: 190 lines in 2 files changed: 181 ins; 2 del; 7 mod
  Patch: https://git.openjdk.org/jdk20u/pull/23.diff
  Fetch: git fetch https://git.openjdk.org/jdk20u.git pull/23/head:pull/23

PR: https://git.openjdk.org/jdk20u/pull/23