* @return true if the password contains a digit, false otherwise
     */
    protected boolean containsDigit(final String password) {
        for (int i = 0; i < password.length(); i++) {
            if (Character.isDigit(password.charAt(i))) {
                return true;
            }
        }
        return false;
    }

    /**
     * Checks if the password contains at least one special character.