public Set<ID> getActualCrashedMembers(GMSMembershipView<ID> oldView) {
    Set<ID> result = new HashSet<>(crashedMembers.size());
    result.addAll(crashedMembers.stream()
        .filter(mbr -> (mbr.getVmKind() != ID.ADMIN_ONLY_DM_TYPE))
        .filter(mbr -> oldView == null || oldView.contains(mbr)).collect(Collectors.toList()));
    return result;
  }
returns the members of this views crashedMembers collection that were members of the given
view. Admin-only members are not counted
geode-membership/src/main/java/org/apache/geode/distributed/internal/membership/gms/GMSMembershipView.java