CA: ProvisioningRequest protobuf marshal error

[elmiko]

Which component are you using?:

/area cluster-autoscaler

What version of the component are you using?:

Component version: 1.34

What k8s version are you using (kubectl version)?: 1.34

kubectl version Output

$ kubectl version

What environment is this in?: cluster-api/aws

What did you expect to happen?: expected ProvisioningRequests to be processed by autoscaler.

What happened instead?: an error was produced while trying to add the Accepted condition to the ProvisioningRequest.

I1124 20:31:58.586737       1 request.go:1038] "Error in request" err="object *v1.ProvisioningRequest does not implement the protobuf marshalling interface and cannot be encoded to a protobuf message"
E1124 20:31:58.586759       1 injector.go:81] failed add Accepted condition to ProvReq default/job-sample-job-h2ctl-da97c-sample-prov-1, err: object *v1.ProvisioningRequest does not implement the protobuf marshalling interface and cannot be encoded to a protobuf message

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

1. run CA with --enable-provisioing-request=true
2. create a ProvisioningRequest (i used Kueue for the purposes of this test)
3. observe logs

Anything else we need to know?: the only related threads i have found are from a long time ago, and seem to reference the headers for the rest client needing to have the proper application/json mime type for the accepted header. that seems unlikely, but i'm going to experiment with the client.

[towca]

@jackfrancis Protobuf marshalling issues for K8s types (albeit here it's a CRD, not a built-in type) sound vaguely related to the marshalling problems from #8660. I haven't dug into that issue, do you think this one could be related?