@JsonIgnore
    public boolean isProxy() {
        return isHostedVespaApplicationWithPredicate(ApplicationInstanceId::isProxy) &&
               Objects.equals(clusterId, ClusterId.ROUTING) &&
               Objects.equals(serviceType, ServiceType.CONTAINER);
    }
Is a config server (and not controller!)
application-model/src/main/java/com/yahoo/vespa/applicationmodel/ServiceCluster.java