agones: Can't apply fleetautoscaler on 1.17.0

What happened: Can’t apply fleetautoscaler on 1.17.0 agones.

$ kubectl apply -f https://raw.githubusercontent.com/googleforgames/agones/release-1.17.0/examples/simple-game-server/fleetautoscaler.yaml

Error from server (InternalError): error when creating "examples/simple-game-server/fleetautoscaler.yaml": Internal error occurred: failed calling webhook "validations.agones.dev": Post "https://agones-controller-service.agones-system.svc:443/validate?timeout=10s": EOF

How to reproduce it (as minimally and precisely as possible):

Create cluster on GKE
$ gcloud container clusters create [CLUSTER_NAME] --cluster-version=1.20 

–tags=game-server 

–scopes=gke-default 

–num-nodes=4 

–no-enable-autoupgrade 

–machine-type=e2-standard-4
$ gcloud config set container/cluster [CLUSTER_NAME]
$ gcloud container clusters get-credentials [CLUSTER_NAME]
$ gcloud compute firewall-rules create game-server-firewall 

–allow udp:7000-8000 

–target-tags game-server 

–description “Firewall to allow game server udp traffic”
Install agones 1.17.0
$ kubectl create namespace agones-system
$ kubectl apply -f https://raw.githubusercontent.com/googleforgames/agones/release-1.17.0/install/yaml/install.yaml
Create fleet
$ kubectl apply -f https://raw.githubusercontent.com/googleforgames/agones/release-1.17.0/examples/simple-game-server/fleet.yaml
Create fleetautoscaler
$ kubectl apply -f https://raw.githubusercontent.com/googleforgames/agones/release-1.17.0/examples/simple-game-server/fleetautoscaler.yaml
-> error!

Anything else we need to know?:

• 1.16.0 work fine
• According to agones-controller logs, nil pointer error is occured

Environment:

• Agones version: 1.17.0
• Kubernetes version (use kubectl version): 1.20+
• Cloud provider or hardware configuration: GKE
• Install method (yaml/helm): yaml

This issue from disscussion on slack