Upgrade ArduinoJson to ^6

[JavanPoirier]

OpenMQTTGateway/platformio.ini

Line 117 in 3db54b4

arduinojson = [email protected]

There is a bug in the current version with serialization/de-serialization causing malformed nested objects. I have updated without any noticeable issues.

[peshovec]

In my personal setup (rf,rf2,pilight and rtl_433) i use ArduinoJson 7.3.0

Had to do some tweak, elsewhere the discovery (rtl_433) messages were not ok
peshovec@b6847f6

This modification was not needed with ArduinoJson 7.2.1

Share that, as it seems ArduinoJson 7 implement some nice goodies - for example ability to safely read json key, even if the key does not exist (returns null in this case). It is claimed that this can lead to smaller code (when refactored).
However containsKey is deprecated in favor of checking the type of the key value (general check, regardless of the type exist too)

Probably it is worth to have in mind if update to latest ArduinoJson is in the plans. Did not dig very deep, based on my observation, potential roadmap could be:

• "one" time effort to go to 7.2.1
• refactor the deprecations (containsKey) when a change in the code is needed , e.g. on demand
• follow the 7.3 and latest.