RFR 8220238 : Enhancing j.l.Runtime/System::gc specification with an explicit 'no guarantee' statement

[Martin Buchholz]

If you are calling System.gc() for correctness (e.g. in a test), it is
probably because some sort of finalization is being triggered.  And that
happens in some Java thread (e.g. Reference Handler) that System.gc() has
no control over.  So in practice, users need to call System.gc() and then
wait for subsequent reference processing somehow.