test/hotspot/jtreg/gc/stress/jfr/TestStressBigAllocationGCEventsWithShenandoah.java fails with both Shenandoah and GenShen because they do not produce the expected JFR event.

It's questionable that purely concurrent collectors will produce that exact event, so it would make sense if purely concurrent collectors such as Shen, GenShen (and Z/GenZ) produce other JFR GC events that the test check for the existence of those events. An alternate version of the test would make sense for these collectors.

Meanwhile, the test should be problem-listed for Shen/GenShen. Note that this test didn't exist in openjdk/tip for Shenandoah, but appears to have been introduced (i.e. copied from G1 et al, tests) during GenShen development.