MQTT Subscription not triggering on Observation Patch on value

[SpeckiJ]

The implementation for updating the result of an Observation is currently missing. Therefore updating the result will not trigger a new mqtt notification. This does not affect new Observations, only subscriptions on the result property of an existing Observation.

https://github.com/SpeckiJ/sensor-things/blob/35c4ecf9a2ce77200c8c1a0d6dcc87558fba4fc1/sensor-things-api-core/src/main/java/org/n52/sta/data/repositories/MessageBusRepository.java#L126

[SpeckiJ]

For v2 this should be fixed by e1f63cd