Virtual threads are always daemon threads, so tests that previously did not explicitly wait for test threads to exit sometimes fail with virtual threads due to the test exiting before the test threads have exited. A join() for each test thread is needed to fix this issue.

com/sun/jdi/DeferredStepTest.java is one such tests. I looked at the other com/sun/jdi failures listed in JDK-8285422 and didn't see any others that might be failing for this same reason.