private static boolean hasExclusiveNodes(VespaModel model, ApplicationContainerCluster cluster) {
        return model.hostSystem().getHosts()
                .stream()
                .flatMap(hostResource -> hostResource.spec().membership().stream())
                .filter(membership -> membership.cluster().id().equals(cluster.id()))
                .anyMatch(membership -> membership.cluster().isExclusive());
    }
Validates that config using s3:// urls is used in public system and with nodes that are exclusive.

@author hmusum
config-model/src/main/java/com/yahoo/vespa/model/application/validation/UrlConfigValidator.java