Test java/lang/management/MemoryMXBean/LowMemoryTest.java is written to cover all existing garbage collectors configurations. Hovewer it makes impossible to run the test with explicitly specified GC. In that way the test fails with the following error message:
Conflicting collector combinations in option list; please refer to the release notes for the combinations allowed.

There's a few options how to fix the test:
1) add @requires vm.gc == "null"
this ensures the test will never be executed if GC is set explicitly;
2) split the test into 4 separate ones, 1 test per GC
in that case we will test only requested configurations