TYPE ST_IotMqttWill :
STRUCT
    sTopic : STRING(255); // topic string (UTF-8) (attend that MQTT topics are case sensitive)
    pPayload : PVOID;
    nPayloadSize : UDINT;
    eQoS : TcIotMqttQos := TcIotMqttQos.ExactlyOnceDelivery; // quality of service between the publishing
client and the broker
    bRetain : BOOL; // if TRUE the broker stores the message in order to send it to new subscribers
END_STRUCT
END_TYPE