RFR: 8314762: Make {@Incubating} conventional

[Pavel Rappo]

Please review this trivial PR.

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/15387/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15387&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314762
  Stats: 6 lines in 3 files changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/15387.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15387/head:pull/15387

PR: https://git.openjdk.org/jdk/pull/15387