public static String getRandomString(int length) {
    StringBuilder sb = new StringBuilder(length);
    for (int i = 0; i < length; i++) {
      sb.append(CHARACTERS.charAt(RANDOM.nextInt(CHARACTERS.length())));
    }
    return sb.toString();
  }
Generates and returns a random Hex String of the specified size
@param size expected key hex string size
@return the hex string thus generated
ambry-test-utils/src/main/java/com/github/ambry/utils/TestUtils.java