The FormAction makes a distinction between the actual required slot, where the full slot_mappings are used and other slots. For example you got a bot that sells train tickets and the required slots are number of seats, departure_place, arrival_place and date. Now the bot utters the utter_ask_arrival_place template
Bot: Where do you want to go?
User: i want to go to london tomorrow
So in this case the required slot was arrival_place, but the user also answered the date. Now, for the required slot, Rasa makes use of the whole specified slot mappings, but for the extra slot (that we did not explicitly ask for at that point!) its just mapped from entities with the exact same name (or some predefined value with the ‘from_trigger_input’), as you see in the code. I was curious whats the reason for this. Why did the developers choose not to use the whole list of entities as specified in the slot_mappings (‘from_entity’)?