docs: protected Pair<String, String> getClientIdAndClientSecret(final WebContext context) {
          val extractor = new BasicAuthExtractor();
          val upc = extractor.extract(context);
          if (upc != null) {
              return Pair.of(upc.getUsername(), upc.getPassword());
          }
          val clientId = context.getRequestParameter(OAuth20Constants.CLIENT_ID);
          val clientSecret = context.getRequestParameter(OAuth20Constants.CLIENT_SECRET);
          return Pair.of(clientId, clientSecret);
      }