ZooKeeper node name sanitization

/**
 * Usually returns a resource name that adheres to the ZooKeeper naming rules. There are some cases that are purposefully not
 * caught by this method. For example, the token "zookeeper" and unicode characters greater then 16 bits in size.
 *
 * @param resource
 * @return
 */
public static String normalize(String resource) {
  if (resource.equals(".")) {
    return "\\x2e";
  }
  if (resource.equals("..")) {
    return "\\x2e\\x2e";
  }
  char[] oldChars = resource.toCharArray();
  char[] newChars = new char[oldChars.length * 6];
  int i = 0;
  for (char oldChar : oldChars) {
    if (oldChar != '/'
        && (0x19 < oldChar && oldChar < 0x7F || 0x9F < oldChar && oldChar < 0xd800 || 0xF8FF < oldChar && oldChar < 0xFFF0)) {
      newChars[i] = oldChar;
      i++;
    } else {
      newChars[i] = '\\';
      newChars[i + 1] = 'x';
      String hexValue = Integer.toHexString(oldChar);
      hexValue.getChars(0, hexValue.length(), newChars, i + 2);
      i += 2 + hexValue.length();
    }
  }
  return new String(newChars, 0, i);
}

/**
 * Returns the xsd:hexBinary representation of the given string.
 */
public static String convertStringToHex(String string) {
  return DatatypeConverter.printHexBinary(string.getBytes());
}

/**
 * Returns the string represented by the xsd:hexBinary input.
 */
public static String convertHexToString(String hex) {
  return new String(DatatypeConverter.parseHexBinary(hex));
}