public List<String> getValidationErrors() {
        List<String> errors = new ArrayList<String>();
     
        if (username == null || username.length() == 0) errors.add("Username is required");
        if (button == null || button.length() == 0) errors.add("Button is required");
        if (errors.size() > 0) return errors;
        
        if (username.matches(".*[<>\"&].*")) errors.add("Username may not contain angle brackets, quotes, greater, less or ampersan"); 
        if (button.matches(".*[<>\"&].*")) errors.add("Username may not contain angle brackets, quotes, greater, less or ampersan");  

        return errors;
    }