In JDK-8208498 we introduced the HeapRegionSetBase::RegionSetKind enum to allow some verification checks about the type of region added to the HeapRegionSet.

Instead of adding enums for new kinds of HeapRegionSets (effectively one for every kind of heapregionset), probably a better solution would be to extend the HRSMtSafeChecker to be used for this purpose too (various verifications).