8314990: Generational ZGC: Strong OopStorage stats reported as weak roots

Reviewed-by: stefank, eosterlund

src/hotspot/share/gc/z/zRootsIterator.cpp

@@ -101,7 +101,7 @@ void ZParallelApply<Iterator>::apply(ClosureType* cl) {
 }
 
 void ZOopStorageSetIteratorStrong::apply(OopClosure* cl) {
-  ZRootStatTimer timer(ZSubPhaseConcurrentWeakRootsOopStorageSet, _generation);
+  ZRootStatTimer timer(ZSubPhaseConcurrentRootsOopStorageSet, _generation);
   _iter.oops_do(cl);
 }