Add 'Authorized Party' field for OIDC extension

[dimitri995]

Hello,

The OIDC standard states that the "aud" (audience) field in the access token is used to indicate which application or service the token is intended for. On the other hand, the "azp" (Authorized Party) field indicates which application the token was issued to. In some situations, the application issuing the token and the target application may be the same, meaning that "azp" and "aud" are equal.

However, it's important to note that the OIDC standard doesn't explicitly state that the audience is optional when "azp" equals "aud." This interpretation can vary from one implementation to another. If Keycloak has chosen to implement this specific interpretation, it means that Keycloak allows OIDC clients not to explicitly specify the audience in their authorization request if "azp" equals "aud" in the access token. This can simplify certain usage scenarios, but it will also depend on the specific needs of your application and how you configure Keycloak.

Is it possible to consider a code modification in order to verify the token with AUZ (Authorized Party) in order to answer this Keycloak implementation case?

https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/extension/oidcauthextension/extension.go#L81

Regards,

Dimitri