PrimaryExpr TypeAssertion |
                PrimaryExpr Arguments .

Selector      = "." identifier .
Index         = "[" Expression [ "," ] "]" .
Slice         = "[" [ Expression ] ":" [ Expression ] "]" |
                "[" [ Expression ] ":" Expression ":" Expression "]" .
TypeAssertion = "." "(" Type ")" .
Arguments     = "(" [ ( ExpressionList | Type [ "," ExpressionList ] ) [ "..." ] [ "," ] ] ")" .
</pre>

- Fixed the example validation rule in godoc:
  
  When configuring a JWT authenticator:
  
  If username.expression uses 'claims.email', then 'claims.email_verified' must be used in
  username.expression or extra[*].valueExpression or claimValidationRules[*].expression.
  An example claim validation rule expression that matches the validation automatically

- When configuring a JWT authenticator:
  

### Promoted CRD Validation Expression Language to Beta

- Added `messageExpression` to `ValidatingAdmissionPolicy`, to set custom failure message via CEL expression. ([#116397](https://github.com/kubernetes/kubernetes/pull/116397), [@jiahuif](https://github.com/jiahuif)) [SIG API Machinery]
- Added a new IPAddress object kind

- Added name validation for dynamic client methods in client-go ([#75072](https://github.com/kubernetes/kubernetes/pull/75072), [@lblackstone](https://github.com/lblackstone))
- CustomResourceDefinition with invalid regular expression in the pattern field of OpenAPI v3 validation schemas are no longer considered structural. ([#78453](https://github.com/kubernetes/kubernetes/pull/78453), [@sttts](https://github.com/sttts))

- When updating a CRD, per-expression cost limit check are now skipped for `x-kubernetes-validations` rules of versions that are not mutated. ([#121460](https://github.com/kubernetes/kubernetes/pull/121460), [@jiahuif](https://github.com/jiahuif))

- Added enforcement of an upper cost bound for DRA evaluations of CEL. The API server and scheduler now enforce an upper bound on the cost and runtime steps required for evaluating a CEL expression. ([#128101](https://github.com/kubernetes/kubernetes/pull/128101), [@pohly](https://github.com/pohly)) [SIG API Machinery and Node]

- Added ports autocompletion for kubectl port-foward command. ([#124683](https://github.com/kubernetes/kubernetes/pull/124683), [@TessaIO](https://github.com/TessaIO)) [SIG CLI]
- Added support for CEL(Common Expression Language) expressions and `additionalProperties` to be used under nested quantifiers in CRD schemas. ([#124381](https://github.com/kubernetes/kubernetes/pull/124381), [@alexzielenski](https://github.com/alexzielenski)) [SIG API Machinery]

- Added a new feature gate `CelValidatingAdmissionExtensibility` to enable expression validation for Admission Control. ([#112792](https://github.com/kubernetes/kubernetes/pull/112792), [@cici37](https://github.com/cici37)) [SIG API Machinery]