docs: @GetMapping(path = {"/otp/qrgen"})
      public void generate(final HttpServletResponse response, final HttpServletRequest request) throws Exception {
          response.setContentType("image/png");
          val key = request.getParameter("key");
          QRUtils.generateQRCode(response.getOutputStream(), key, QRUtils.WIDTH_LARGE, QRUtils.WIDTH_LARGE);
      }