A 8s "non-GC world stop JVM pause" during snapshot writes

Attached GCLog.log.0.current has this:

2018-09-05T18:23:40.277+0000: 39892.345: Total time for which application threads were stopped: 8.3785112 seconds, Stopping threads took: 8.3765855 seconds

Attached Run.jfr (7z) provided by Ericsson, from their internal downstream distribution based on Boron. (This is the same that they made available via the filehosting.org link on this SO QA. Best analyzed using the JDK Mission Control from OpenJDK v11 from http://jdk.java.net/jmc/. Produced via https://wiki.opendaylight.org/view/HowToProfilePerformance.)