[jdk21] RFR: 8310061: Note if implicit annotation processing is being used

[Joe Darcy]

Backport.

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Commit messages:
 - Backport 3df36c4f101e094d6f6beccadc004742b47d045a

Changes: https://git.openjdk.org/jdk21/pull/80/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21&pr=80&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310061
  Stats: 340 lines in 10 files changed: 328 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk21/pull/80.diff
  Fetch: git fetch https://git.openjdk.org/jdk21.git pull/80/head:pull/80

PR: https://git.openjdk.org/jdk21/pull/80