Conversion Webhook does not implement necessary v1 conversions

[WanzenBug]

What happened:

The conversion webhook for the groupsnapshot.storage.k8s.io API group refuses any conversion that involves the v1 version. The volumegroupsnapshotcontents CRD serves v1beta1, v1beta2 and v1, with v1beta2 as the storage version and spec.conversion.strategy: Webhook. Because v1 is a served, non-storage version, the API server calls the webhook to convert v1 <-> v1beta2 on every access at v1 (create/get/list). The webhook only implements conversions between v1beta1 and v1beta2 -- it has no case for v1 -- so it rejects the request:

conversion webhook for groupsnapshot.storage.k8s.io/v1, Kind=VolumeGroupSnapshotContent failed:
unexpected conversion version from "groupsnapshot.storage.k8s.io/v1" to "groupsnapshot.storage.k8s.io/v1beta2"

What you expected to happen:

Conversions involving v1 succeed. Since v1 and v1beta2 are structurally identical, the webhook should treat v1 <-> v1beta2 as an identity conversion (and handle v1 <-> v1beta1 the same way it handles v1beta2 <-> v1beta1) rather than returning "unexpected conversion version". Creating/reading a VolumeGroupSnapshotContent at v1 should work whenever it works at v1beta2.

How to reproduce it:

On a cluster with the group snapshot CRDs and the conversion webhook running, submit a VolumeGroupSnapshotContent at the v1 version. Server-side dry run is enough -- nothing is persisted and no CSI call is made (the failure happens in the API server / webhook, before the driver is ever consulted, so it is driver-agnostic):

# vgsc-v1.yaml
apiVersion: groupsnapshot.storage.k8s.io/v1
kind: VolumeGroupSnapshotContent
metadata:
  name: conversion-webhook-test
spec:
  deletionPolicy: Retain
  driver: example.csi.k8s.io          # value is irrelevant; driver is never called
  source:
    groupSnapshotHandles:
      volumeGroupSnapshotHandle: test-group-handle
      volumeSnapshotHandles:
        - test-snapshot-handle
  volumeGroupSnapshotRef:
    apiVersion: groupsnapshot.storage.k8s.io/v1
    kind: VolumeGroupSnapshot
    name: conversion-webhook-test-vgs
    namespace: default

$ kubectl apply --dry-run=server -f vgsc-v1.yaml
Error from server: … conversion webhook for groupsnapshot.storage.k8s.io/v1, Kind=VolumeGroupSnapshotContent
failed: unexpected conversion version from "groupsnapshot.storage.k8s.io/v1" to "groupsnapshot.storage.k8s.io/v1beta2"

Submitting the same object at v1beta2 (the storage version, no conversion needed) succeeds, confirming the failure is limited to conversions that touch v1.

CRD version setup for reference:

$ kubectl get crd volumegroupsnapshotcontents.groupsnapshot.storage.k8s.io \
    -o jsonpath='{range .spec.versions[*]}{.name}{" served="}{.served}{" storage="}{.storage}{"\n"}{end}'
v1       served=true storage=false
v1beta1  served=true storage=false
v1beta2  served=true storage=true
$ kubectl get crd volumegroupsnapshotcontents.groupsnapshot.storage.k8s.io -o jsonpath='{.spec.conversion.strategy}'
Webhook

Environment:

• Driver version: external-snapshotter v8.6.0 -- snapshot-controller, conversion-webhook, and the csi-snapshotter sidecar all report "Version" version="v8.6.0". (CSI driver in our setup: LINSTOR CSI linstor.csi.linbit.com`, but the bug is driver-independent.)
• Kubernetes version (use kubectl version): v1.36.2 and v1.33.13 (both affected)
• OS (e.g. from /etc/os-release): AlmaLinux 9
• Install tools: Helm Chart: https://artifacthub.io/packages/helm/piraeus-charts/snapshot-controller
• Others: CRD volumegroupsnapshotcontents.groupsnapshot.storage.k8s.io serves v1beta1/v1beta2/v1, storage version v1beta2, spec.conversion.strategy: Webhook

[taaahaaa]

/assign

I have a fix for this: convertGroupSnapshotCRD only matches on v1beta2, so any conversion involving the served v1 version falls through to the default branch. Since v1 was promoted from v1beta2 without schema changes, v1 <-> v1beta2 is an identity conversion and v1 <-> v1beta1 reuses the existing logic. Will open a PR shortly.