RFR: 8279643: JFR: Explain why path is sometimes missing from FileRead and FileWrite events

[Erik Gahlin]

Hi,

Could I have a review of an enhancement that explains why the path fields for the FileRead and FileWrite events sometimes miss a value.

Testing: jdk/jdk/jfr

Thanks
Erik

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Commit messages:
 - Initial

Changes: https://git.openjdk.java.net/jdk/pull/6995/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6995&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8279643
  Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6995.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6995/head:pull/6995

PR: https://git.openjdk.java.net/jdk/pull/6995