responseType
OIDC: REQUIRED. OAuth 2.0 Response Type value that determines the authorization processing flow to be used, including what parameters are returned from the endpoints used. When using the Authorization Code Flow, this value is code.
The OAuth 2.0 specification allows for registration of space-separated response_type parameter values. If a Response Type contains one of more space characters (%20), it is compared as a space-delimited list of values in which the order of values does not matter.
For OpenID4VP, this is typically vp_token.
Optional when JAR (RFC9101) is used.