Description of problem:
OpenShift OAuth server does not fully implement PKCE (RFC 7636) support. While the OAuth configuration accepts code_challenge_method=S256, it fails to generate and include the required code_challenge parameter in the authorization request to the OpenID provider.

Version-Release number of selected component:
OpenShift Container Platform 4.17
Component: oauth-server

How reproducible:
100% - Consistently reproducible when configuring OpenID provider with PKCE requirement

Steps to Reproduce:
1. Configure OpenShift OAuth with OpenID provider that requires PKCE:
```yaml
apiVersion: config.openshift.io/v1
kind: OAuth
metadata:
name: cluster
spec:
identityProviders:

• name: eu-login
  type: OpenID
  openID:
  extraAuthorizeParameters:
  code_challenge_method: "S256"
  clientID: <client_id>
  claims:
  preferredUsername: ["preferred_username"]

Attempt to authenticate using the OpenID provider
Check oauth-openshift pod logs

Actual results:

Authorization request missing code_challenge parameter:

GET /oauth/authorize?client_id=<client_id>&code_challenge_method=S256&redirect_uri=...

Error in oauth-openshift logs:
"Error handling request: Invalid request: Missing CodeChallenge (PKCE - RFC 7636)"

Expected results:

OAuth server should generate code_verifier
Calculate code_challenge using S256 method
Include both code_challenge_method and code_challenge in authorization request:

GET /oauth/authorize?client_id=<client_id>&code_challenge_method=S256&code_challenge=<calculated_challenge>&redirect_uri=...

Additional info:

Logs show the configuration is accepted but code_challenge is not generated
Working applications with same OpenID provider include both parameters
Example of working request from another application:

GET /cas/oauth2/authorize?client_id=<CLIENT_ID>&code_challenge=Fke_zHXCFON5R3SYx__RBH-N85FKscra2EIdDtPoEcU&code_challenge_method=S256...

OAuth server logs confirm PKCE parameters are missing in the request
This appears to be a limitation in the current OpenShift OAuth server implementation