Last Will seems to be set incorrectly

[ajongen]

The availability topic in MQTT is not set to "offline" when the wordclock e.g. is turn off (at least in my configuration). I suspect that the line where it is set:

mqtt_client_.setWill(availabilityTopic.c_str(), "offline");

should also set the RETAIN flag to TRUE and maybe also the QOS to 0. This by the looks of the code in the used MQTT lib:

void MQTTClient::setWill(const char topic[], const char payload[], bool retained, int qos)