code: public String getRandomChars(final int minLength, final int maxLength) {
      validateMinMaxParams(minLength, maxLength);
      StringBuilder sb = new StringBuilder(maxLength);
  
      int length = minLength;
      if (maxLength != minLength) {
        length = length + random.nextInt(maxLength - minLength);
      }
      while (length > 0) {
        sb.append(getRandomChar());
        length--;
      }
      return sb.toString();
    }
docs: Return a string containing between <code>length</code> random characters
  
  @param minLength minimum number of characters to use in the string
  @param maxLength maximum number of characters to use in the string
  
  @return A string containing <code>length</code> random characters