I'm running a K8s cluster, serving a gRPC service with an Enterprise Service Proxy serving both gRPC and REST over HTTPS.

I'm trying to enable CORS for this endpoint, but I can't get it working. 

Here's my endpoint config:

```
...
endpoints:
- name: <my-service>.endpoints.<my-project>.cloud.goog
  target: <ENDPOINT_IP>
  allow_cors: true

```

I've updated the endpoint and updated the ESP config. I've confirmed that there's a section in `/etc/nginx.d/service.json` or something that contains something about CORS being enabled.

However, when I issue an OPTIONS request to my endpoint, I get back the error message `The service does not allow CORS traffic.`

I'm out of ideas. Does anyone know how I can enable CORS for my endpoint?