code: public static String shuffle(final String value) {
          validate(value, NULL_STRING_PREDICATE, NULL_STRING_MSG_SUPPLIER);
          String[] chars = chars(value);
          Random random = new Random();
          for (int i = 0; i < chars.length; i++) {
              int r = random.nextInt(chars.length);
              String tmp = chars[i];
              chars[i] = chars[r];
              chars[r] = tmp;
          }
          return Arrays.stream(chars).collect(joining());
      }
docs: It returns a string with its characters in random order.
  
  @param value The input String
  @return The shuffled String