[jdk21] RFR: 8311264: JavaDoc index comparator is not transitive

Thu Jul 6 09:43:14 UTC 2023

This bug existed before 21, but [JDK-8286470](https://bugs.openjdk.org/browse/JDK-8286470) triggered it and caused some strange and possibly non-deterministic ordering of items in the JavaDoc index pages, which caused failures reported in [JDK-8309233](https://bugs.openjdk.org/browse/JDK-8309233). Since the fix is fairly simple I think it should be backported to 21.

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Commit messages:
 - Backport 0741cd3289ccc89777449711ab20d6c32711f494

Changes: https://git.openjdk.org/jdk21/pull/100/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21&pr=100&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311264
  Stats: 124 lines in 4 files changed: 88 ins; 9 del; 27 mod
  Patch: https://git.openjdk.org/jdk21/pull/100.diff
  Fetch: git fetch https://git.openjdk.org/jdk21.git pull/100/head:pull/100

PR: https://git.openjdk.org/jdk21/pull/100