String signature = "3U6JAfMJPE8i1PpYTKfHHsLp9xu7iS3YBmK2Mg8kkygpH57xyrHWq39mp39xr6FgM447R7dqwDgXVMq79Dm7HnwT";
final ConfirmedTransaction confirmedTransaction = client.getApi().getConfirmedTransaction(signature);
String data = confirmedTransaction.getTransaction().getMessage().getInstructions().get(0).getData();