private static Map<String, Object> ToMap(String e, String[] bannedPrefixes) {
        Map<String, Object> map = new HashMap<>();
        map.put("card", e);
        map.put("isValid", isValid(e));
        map.put("isAllowed", isAllowed(e, bannedPrefixes));
        return map;
    }
Why Did you create this class? what does it do?
src/codeforces/ValidateCard.java