RFR: 7992: Add API to easily write annotated Java JFR events

[Jaroslav Bachorik]

Yay. Non empty PR body to make jcheck happy.

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Commit messages:
 - Update copyright year
 - JMC-7992: Add API to easily write annotated Java JFR events

Changes: https://git.openjdk.org/jmc/pull/457/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=457&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-7992
  Stats: 409 lines in 4 files changed: 402 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jmc/pull/457.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/457/head:pull/457

PR: https://git.openjdk.org/jmc/pull/457