code: private static String constructOpenIdUrl(String issuer) {
      String url = issuer;
      if (!URI.create(issuer).isAbsolute()) {
        // Use HTTPS if the protocol scheme is not specified in the URL.
        url = HTTPS_PROTOCOL_PREFIX + issuer;
      }
      if (!url.endsWith("/")) {
        url += "/";
      }
      return url + OPEN_ID_CONFIG_PATH;
    }
docs: Construct the OpenID discovery URL based on the issuer.