RFR: 8303208 JFR: 'jfr print' displays incorrect timestamps

[Erik Gahlin]

Could I have a review of a PR that fixes incorrect display of timestamp for the 'jfr' tool. 

Testing: jdk/jdk/jfr

Thanks
Erik

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Commit messages:
 - Fix indentation
 - Initial

Changes: https://git.openjdk.org/jdk/pull/12757/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12757&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303208
  Stats: 6 lines in 1 file changed: 5 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12757.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12757/head:pull/12757

PR: https://git.openjdk.org/jdk/pull/12757