The origin of this gist: https://blog.cloudboost.io/copy-export-a-cloud-firestore-database-388cde99259b
The schema is for example only, it's must be modified according to the firestore database.
Quoting Bruno Braga
"this schema is how your DB is organized in a tree structure. You don't have to care about the Documents but you do need to inform the name of your collections and any subcollections, in this case we have two collections called users and groups, the all have their documents, but the collection users has its own subcollections, friends and groups, which again have their own subcollection, messages."
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