RFR: 8339789: Use index and definition tags in AnnotatedElement

[Joe Darcy]

Use index and definition tags in AnnotatedElement.

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Commit messages:
 - JDK-8339789: Use index and definition tags in AnnotatedElement

Changes: https://git.openjdk.org/jdk/pull/20919/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20919&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339789
  Stats: 7 lines in 1 file changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/20919.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20919/head:pull/20919

PR: https://git.openjdk.org/jdk/pull/20919