requestToken
suspend fun requestToken(oauthClient: OAuthClient, nonce: String, codeVerifier: String, code: String, keyPair: DpopKeyPair? = null): OAuthToken
Request an access token using the provided OAuth client, nonce, code verifier, and authorization code.
You are highly encouraged to verify that the state received in the callback matches the state returned by buildAuthorizationRequest before calling this method, to prevent CSRF attacks. You can also pass in an optional DPoP key pair to sign the request with DPoP, otherwise a new key pair will be generated for you.