anchor.diff:    }
   
     /// Refresh an authorization token.
  -  Future<AuthorizationTokenResponse> refreshAuthorizationToken(
  +  FutureOr<AuthorizationTokenResponse> refreshAuthorizationToken(
         Client client,
         String refreshToken,
         Iterable<String> scopes,
  
positive.code:   }
  
    /// Exchanges an authorization code for an authorization token.
    Future<AuthorizationTokenResponse> exchangeAuthorizationCodeForToken(
        String authCode,
        String redirectUri,
        RequestContext req,
  
negative.code:   ///
    /// Note that in cases where this is called, there is no guarantee
    /// that the user agent has not been compromised.
    FutureOr<AuthorizationTokenResponse> implicitGrant(
        Client client,
        String redirectUri,
        Iterable<String> scopes,
  