code: public AuthenticationRequestBuilder getAuthorizationEndPoint() {
      for(Authentication auth : authentications.values()) {
       if (auth instanceof OAuth) {
          OAuth oauth = (OAuth) auth;
          return oauth.getAuthenticationRequestBuilder();
        }
      }
      return null;
    }
docs: Helper method to configure authorization endpoint of the first oauth found in the authentications (there should be only one)
  @return