RFR: 8230767: FlightRecorderListener returns null recording

[Erik Gahlin]

Hi,

Could I please have a review of this fix to the FlightRecorderListener.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8230767

Webrev:
http://cr.openjdk.java.net/~egahlin/8230767/

Testing:
/test/jdk/jdk/jfr

Thanks
Erik