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