code: public static String getRandomPasswordString(final int stringLength) {
  
      StringBuilder stringBuilder = getStringBuild();
      for (int i = 0; i < stringLength; i++) {
        stringBuilder.append(getRandomPasswordChar());
      }
      return stringBuilder.toString();
    }
docs: Returns a random given length size passowrd string([a-zA-Z0-9]+).
  
  @param stringLength the length of the random passowrd you want.
  @return a random given length size passowrd string([a-zA-Z0-9]+).