for (int i = 0; i < topics.length; i++) {
qos[i] = (byte) onSubscribe(command, topics[i]).ordinal();
}
SUBACK ack = new SUBACK();
ack.messageId(command.messageId());
ack.grantedQos(qos);
try {
getMQTTTransport().sendToMQTT(ack.encode());
} catch (IOException e) {
LOG.warn("Couldn't send SUBACK for " + command, e);
}