public static ClusterMembership from(String stringValue, Version vespaVersion, Optional<DockerImage> dockerImageRepo) {
        return from(stringValue, vespaVersion, dockerImageRepo, ZoneEndpoint.defaultEndpoint);
    }
@Test
    void testServiceInstanceWithGroup() {
        ClusterSpec cluster = ClusterSpec.specification(ClusterSpec.Type.content, ClusterSpec.Id.from("id1"))
                               .group(ClusterSpec.Group.from(4))
                               .vespaVersion("6.42")
                               .build();
        assertContentServiceWithGroup(ClusterMembership.from(cluster, 37));
    }