In TestClassUnloadEvent.java (and other files)

The G1 part of the comment is not true, check if the JFR part is still true.

/**
 * System.gc() will trigger class unloading if -XX:+ExplicitGCInvokesConcurrent is NOT set.
 * If this flag is set G1 will never unload classes on System.gc() and
 * CMS will not guarantee that all semantically dead classes will be unloaded.
 * As far as the "jfr" key guarantees no VM flags are set from the outside
 * it should be enough with System.gc().
 */