Backport of openjdk/jdk#14312 to limit first character keys in the static JavaDoc index pages to valid Java identifier start characters.
------------- Commit messages: - Backport 21f6d83358458c2e5a6cc1bc19a6a33b3262f990 Changes: https://git.openjdk.org/jdk21/pull/30/files Webrev: https://webrevs.openjdk.org/?repo=jdk21&pr=30&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8309471 Stats: 103 lines in 3 files changed: 87 ins; 0 del; 16 mod Patch: https://git.openjdk.org/jdk21/pull/30.diff Fetch: git fetch https://git.openjdk.org/jdk21.git pull/30/head:pull/30 PR: https://git.openjdk.org/jdk21/pull/30
