title: Firestore query for subcollections on a deleted document
body: <p>When using the Firebase console it is possible to see all documents and collections, even subcollections where the path has "documents" that do not exist.</p>
  
  <p>This is illustrated in the picture included here, and as stated in the docs and on the screenshot as well. These documents won't appear in queries or snapshots. So how does the console find these nested subcollections, when a query does not return them?
  <a href="https://i.stack.imgur.com/AsLrl.png" rel="noreferrer"><img src="https://i.stack.imgur.com/AsLrl.png" alt="Picture showing the Firebase console"></a></p>
  
  <p>Is it possible, somehow, to list these documents. Since the console can do it, it seems there must be a way.
  And if it is possible to find these documents, is it possible to create a query that fetches all the documents that are non-existant but limited to those that have a nested subcollection? (Since the set of all non-existant documents would be infinite)</p>