docs: private String getRandomStr() {
          String base = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
          Random random = new Random();
          StringBuffer sb = new StringBuffer();
          for (int i = 0; i < 16; i++) {
              int number = random.nextInt(base.length());
              sb.append(base.charAt(number));
          }
          return sb.toString();
      }