apollo-adminservice/src/main/java/com/ctrip/framework/apollo/adminservice/controller/NamespaceController.java/NamespaceController/findPublicNamespaceForAssociatedNamespace
class NamespaceController:  @GetMapping("/apps/{appId}/clusters/{clusterName}/namespaces/{namespaceName}/associated-public-namespace")
  public NamespaceDTO findPublicNamespaceForAssociatedNamespace(@PathVariable String appId,
                                                                @PathVariable String clusterName,
                                                                @PathVariable String namespaceName) {
    Namespace namespace = namespaceService.findPublicNamespaceForAssociatedNamespace(clusterName, namespaceName);

    if (namespace == null) {
      throw new NotFoundException("public namespace not found. namespace:%s", namespaceName);
    }

    return BeanUtils.transform(NamespaceDTO.class, namespace);
  }