docs: public static final String padHexString(int num, int width) {
          final String zeroPad = "0000000000000000";
  
          String str = Integer.toHexString(num);
          final int length = str.length();
  
          if (length >= width)
              return str;
  
          StringBuilder buffer = new StringBuilder(zeroPad.substring(0, width));
          buffer.replace(width - length, width, str);
          return buffer.toString();
      }