BlackjackHand blackjackHand = new BlackjackHand(
new Card('6', SPADES),
Arrays.asList(new Card('4', CLUBS), new Card('A', HEARTS)));
Moshi moshi = new Moshi.Builder().build();
JsonAdapter<BlackjackHand> jsonAdapter = moshi.adapter(BlackjackHand.class);
String json = jsonAdapter.toJson(blackjackHand);
System.out.println(json);