delete method
Deletes the document referred to by this DocumentReference.
Implementation
Future<void> delete() async {
// if we don't have the document ID, get it first.
if (id == null) _id = (await get())?.id;
if (_id == null) return; // early out if this document does not exist
await service
._delete(documentUri)
// we don't need the response for anything, but check for exceptions
.then((response) => service._handleResponse(response));
}