✨ Add .spec.upgrade.external.generateUpgradePlanExtension field to ClusterClass

[sivchari]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Part of #12720

/area clusterclass

[sbueringer]

/assign @fabriziopandini

[fabriziopandini]

Changes SGTM, might be just worth leaving a note on this PR about the fact that when this change will merge, the new API field, even if set, won't have any effect until other also tasks documented in #12720 will be completed in follow up PRs.

@sbueringer In the tracking issue we have a note to add corresponding validation for the new API field, but as far as I remember we decided that the runtime extension can work in combination with Kubernetes versions (with the latter used only for validation of cluster.spec.version if both are set). Is this correct?

[sbueringer]

@sbueringer In the tracking issue we have a note to add corresponding validation for the new API field, but as far as I remember we decided that the runtime extension can work in combination with Kubernetes versions (with the latter used only for validation of cluster.spec.version if both are set). Is this correct?

Yes this is correct. After our last discussion the "validation" was only referring to min length / max length etc (#12720 (comment))

[sbueringer]

Thx!
/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 7f2cdcb60fabfc8cf6420b6ab99115864be42b82

[k8s-ci-robot]

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