Support of MQTT Last Will and testament #49
Description
Via MQTT it is possible to provide a last will: https://www.hivemq.com/blog/mqtt-essentials-part-9-last-will-and-testament/:
"Last Will and Testament (LWT) is a powerful feature in MQTT that allows clients to specify a message that will be automatically published by the broker on their behalf, if or when an unexpected disconnection occurs. It provides a reliable means of communication and ensures that clients can gracefully handle disconnections without leaving topics in an inconsistent state. This feature is particularly valuable when clients must notify others of their unavailability or convey important information upon an unexpected disconnection."
The PubSub SDK should support the possibility to specify such a “last will” for each pubished dataset which should then be provided as “last will” via MQTT.