Slot filling - Don't understand the expression "form{"name": null}" in documentation

Hello,

Looking at the documentation about slot filling (Slot Filling), I still don’t understand the parameter form{“name”: null} in the following example:

chitchat

  • request_restaurant
    • restaurant_form
    • form{“name”: “restaurant_form”}
  • chitchat
    • utter_chitchat
    • restaurant_form
    • form{“name”: null}

Thanks!