private static void assertProvisioned(int nodeCount, ClusterSpec.Id id, ClusterSpec.Id combinedId,
                                          ClusterSpec.Type type, VespaModel model) {
        assertEquals(nodeCount,
                     model.hostSystem().getHosts().stream()
                          .map(h -> h.spec().membership().get().cluster())
                          .filter(spec -> spec.id().equals(id) && spec.type().equals(type) && spec.combinedId().equals(Optional.ofNullable(combinedId)))
                          .count(),
                     "Nodes in cluster " + id + " with type " + type + (combinedId != null ? ", combinedId " + combinedId : ""));
    }
Recreate the combination used in some factory tests
config-model/src/test/java/com/yahoo/config/model/provision/ModelProvisioningTest.java