RFR: 8342707: Prepare Gatherers for graduation from Preview [v2]

[Viktor Klang]

> Make final adjustments to drop PreviewFeature and updating the @ since markers.

Viktor Klang has updated the pull request incrementally with one additional commit since the last revision:

  Updating copyright years and removing an unneccessary import for Gatherers

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21686/files
  - new: https://git.openjdk.org/jdk/pull/21686/files/194c7695..189f2f85

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21686&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21686&range=00-01

  Stats: 4 lines in 2 files changed: 0 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/21686.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21686/head:pull/21686

PR: https://git.openjdk.org/jdk/pull/21686