ValidatingAdmissionPolicy page does not clearly explain the differences between `has()` and `in` for maps vs fields

[EraYaN]

This is a Feature Request

What would you like to be added

Some extra language helping with the differences between has() and in for maps vs fields.

Why is this needed

> CEL provides has(), which checks if the key passed to it exists.

Seems to indicate that a map would work (key) for has(). But it apparently it doesn't (need to use in) or the fact that the a["b"] notation breaks has() as well. (Based on some comments from this issue: kubernetes/kubernetes#118230)

Comments

Split of from: #41391
About page: https://kubernetes.io/docs/reference/access-authn-authz/validating-admission-policy/

[Ritikaa96]

/sig auth api-machinery
/language en

[Nitishupkr]

can i work on this issue

[stlaz]

@jpbetz would you please have a look?

[jpbetz]

https://kubernetes.io/docs/reference/using-api/cel/ . is probably where this should be explained.

@Nitishupkr you're welcome to self assign if you're interested in getting this addressed.

[aramase]

/triage accepted