Insights Hub Custom JSON template for MC IoT Extensions

I have checked the documentation: https://developer.mindsphere.io/howto/howto-mqtt-mciot.html for using MQTT but it is so far no clear for me I'm allowed to publish a JSON string to MC IoT Extension. I have not found a formula to do this.

MC IoT Extensions currently doesn't support custom JSON format . 

You can use measurements, alarms, events templates as defined templates.

Here is the cheat sheet for MQTT templates:

https://documentation.mindsphere.io/resources/pdf/mqtt_cheatsheet.pdf

Notes