Emit warnings when users create CRDs with deprecated fields

[lbernick]

Feature request

It would be great to have our admission webhook emit a warning when a user creates a CRD with a deprecated field but not reject it entirely. Knative allows us to set an error "level" (via func(*FieldError).At) which is meant for this use case but we likely want knative/pkg#2514 to be resolved before doing this.

[JeromeJu]

/assign

[tekton-robot]

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[tekton-robot]

Stale issues rot after 30d of inactivity.
Mark the issue as fresh with /remove-lifecycle rotten with a justification.
Rotten issues close after an additional 30d of inactivity.
If this issue is safe to close now please do so with /close with a justification.
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/lifecycle rotten

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[tekton-robot]

Rotten issues close after 30d of inactivity.
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/close

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[tekton-robot]

@tekton-robot: Closing this issue.

In response to this:

Rotten issues close after 30d of inactivity.
Reopen the issue with /reopen with a justification.
Mark the issue as fresh with /remove-lifecycle rotten with a justification.
If this issue should be exempted, mark the issue as frozen with /lifecycle frozen with a justification.

/close

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[tekton-robot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale with a justification.
Stale issues rot after an additional 30d of inactivity and eventually close.
If this issue is safe to close now please do so with /close with a justification.
If this issue should be exempted, mark the issue as frozen with /lifecycle frozen with a justification.

/lifecycle stale

Send feedback to tektoncd/plumbing.

[vdemeester]

/lifecycle frozen