for (ArrayList<KeyValue> row : rows) {
KeyValue kv = row.get(0);
byte[] expected = kv.value();
String userId = new String(kv.key());
PutRequest put = new PutRequest(
TABLE_NAME, kv.key(), kv.family(),
kv.qualifier(), mkNewPassword(expected));
Deferred<Boolean> d = client.compareAndSet(put, expected)
.addCallback(new InterpretResponse(userId))
.addCallbacks(new ResultToMessage(), new FailureToMessage())
.addCallback(new SendMessage());