RFR: JDK-8282462: Remove unnecessary use of @SuppressWarnings("preview")

[Joe Darcy]

Remove unneeded @SuppressWarnings("preview") annotations now that records are final. I'll update copyrights if neededbefore pushing. Thanks.

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Commit messages:
 - Update copyrights.
 - JDK-8282462: Remove unnecessary use of @SuppressWarnings("preview")

Changes: https://git.openjdk.java.net/jdk/pull/7638/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7638&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282462
  Stats: 9 lines in 4 files changed: 0 ins; 5 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7638.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7638/head:pull/7638

PR: https://git.openjdk.java.net/jdk/pull/7638