docs: public static String toHexString(byte[] b, int offset, int length) {
          StringBuilder buf = new StringBuilder();
          for (int i = offset; i < offset + length; i++) {
              int bi = 0xff & b[i];
              int c = '0' + (bi / 16) % 16;
              if (c > '9') {
                  c = 'A' + (c - '0' - 10);
              }
              buf.append((char) c);
              c = '0' + bi % 16;
              if (c > '9') {
                  c = 'a' + (c - '0' - 10);
              }
              buf.append((char) c);
          }
          return buf.toString();
      }