private boolean existsHostsWithClusterControllerConfigId(VespaModel model) {
        boolean found = false;
        for (HostResource h : model.hostSystem().getHosts()) {
            for (Service s : h.getServices()) {
                if (s.getConfigId().equals("admin/cluster-controllers/0")) {
                    found = true;
                }
            }
        }
        return found;
    }
Test for creating cluster controllers under the admin tag.
config-model/src/test/java/com/yahoo/vespa/model/admin/ClusterControllerTestCase.java