RFR: 8342642: Class loading failure due to archived map issue in ModuleLoaderMap.Mapper

[Jiangli Zhou]

Moved from https://github.com/openjdk/jdk/pull/21672/commits/ade90fb51d1e3652910a3b46775522b730306e16:

Please review the fix that uses String type for the mapped value in ModuleLoaderMap.Mapper map (Map<String, String>). Please see details in https://bugs.openjdk.org/browse/JDK-8342642, thanks.

Existing comment threads from closed https://github.com/openjdk/jdk/pull/21672/commits/ade90fb51d1e3652910a3b46775522b730306e16:
- https://github.com/openjdk/jdk/pull/21672#issuecomment-2436358591
- https://github.com/openjdk/jdk/pull/21672#issuecomment-2437465648
- https://github.com/openjdk/jdk/pull/21672#issuecomment-2438567642
- https://github.com/openjdk/jdk/pull/21672#issuecomment-2436262114
- https://github.com/openjdk/jdk/pull/21672#issuecomment-2437501231

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Commit messages:
 - - Reflect review feedback:
 - Use String instances as the loader indexes in ModuleLoaderMap.Mapper map.

Changes: https://git.openjdk.org/jdk/pull/21722/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21722&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342642
  Stats: 12 lines in 1 file changed: 0 ins; 1 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/21722.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21722/head:pull/21722

PR: https://git.openjdk.org/jdk/pull/21722