docs: public static void writeHexBytes(byte[] o, int from, byte[] b) {
  
          int len = b.length;
  
          for (int i = 0; i < len; i++) {
              int c = ((int) b[i]) & 0xff;
  
              o[from++] = HEXBYTES[c >> 4 & 0xf];
              o[from++] = HEXBYTES[c & 0xf];
          }
      }