class MapUtils {

    public static <K, V> String toString(Map<K, V> map) {
        if (map == null) return "";
        if (map.isEmpty()) return "{}";

        StringBuilder result = new StringBuilder();
        for (Map.Entry<K, V> entry : map.entrySet()) {
            result.append(String.format(", %s -> %s ", entry.getKey().toString(), entry.getValue().toString()));
        }
        return "{" + result.substring(1) + "}";
    }

    private  MapUtils();

}