Invalid Gateway in networking/v1alpha3/gateway.proto

The definition of some-config-namespace/my-gateway is invalid in _networking/v1alpha3/gateway.proto_ and https://preliminary.istio.io/docs/reference/config/networking/v1alpha3/gateway/

```
* error validating resource (networking.istio.io/v1alpha3, Kind=Gateway Name=my-gateway Namespace=): port names in servers must be unique: duplicate name https
```