Mqtt.publish_json multi level

Hello,

I need to send a json through mqtt with multi level like : {"topic":"loic","message":"coucou","priority":5,"tags":["grinning","snail"]}, how can I do that with mqtt.publish_json. Something like that :

on_...:
  then:
    - mqtt.publish_json:
        topic: the/topic
        payload: |-
          root["topic"] = "loic";
          root["message"] = "coucou";
          root["priority"] = 5;
          root["tags"] = ["grinning","snail"];

Is that possible ?

Thank in advance for your return