apollo-adminservice/src/main/java/com/ctrip/framework/apollo/adminservice/controller/NamespaceController.java/NamespaceController/delete
class NamespaceController:  @DeleteMapping("/apps/{appId}/clusters/{clusterName}/namespaces/{namespaceName:.+}")
  public void delete(@PathVariable("appId") String appId,
                     @PathVariable("clusterName") String clusterName,
                     @PathVariable("namespaceName") String namespaceName, @RequestParam String operator) {
    Namespace entity = namespaceService.findOne(appId, clusterName, namespaceName);
    if (entity == null) {
      throw new NotFoundException("namespace not found for %s %s %s", appId, clusterName,
          namespaceName);
    }

    namespaceService.deleteNamespace(entity, operator);
  }