private boolean matchNamespaces(final KubernetesInstance kubernetesInstance) {
        return CollectionUtils.isEmpty(this.kubernetesConfig.getNamespaces()) ? true : this.kubernetesConfig.getNamespaces().contains(kubernetesInstance.getNamespace());
    }
get all serviceInstance.
@param serviceId service identifier
@return list of serviceInstance
shenyu-registry/shenyu-registry-kubernetes/src/main/java/org/apache/shenyu/registry/kubernetes/KubernetesClient.java