MQTTClient_willOptions defines the MQTT "Last Will and Testament" (LWT) settings for the client. In the event that a client unexpectedly loses its connection to the server, the server publishes the LWT message to the LWT topic on behalf of the client. This allows other clients (subscribed to the LWT topic) to be made aware that the client has disconnected. To enable the LWT function for a specific client, a valid pointer to an MQTTClient_willOptions structure is passed in the MQTTClient_connectOptions structure used in the MQTTClient_connect() call that connects the client to the server. The pointer to MQTTClient_willOptions can be set to NULL if the LWT function is not required.
The eyecatcher for this structure. must be MQTW.
The version number of this structure. Must be 0
The LWT topic to which the LWT message will be published.
The LWT payload.
The retained flag for the LWT message (see MQTTClient_message.retained).