RFR: 8294151: JFR: Unclear exception message when dumping stopped in memory recording

[Erik Gahlin]

Hi


Could I have a review of a change that updates the specification for the Recording::dump(Path) method and the exception message if the method fails. 

Testing: jdk/jdk/jfr

Thanks
Erik

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Commit messages:
 - Initial

Changes: https://git.openjdk.org/jdk/pull/10488/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10488&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294151
  Stats: 48 lines in 4 files changed: 38 ins; 1 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/10488.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10488/head:pull/10488

PR: https://git.openjdk.org/jdk/pull/10488