update method
Updates a given document
.
If the document does not yet exist, an exception will be thrown.
Implementation
void update(DocumentReference document, Map<String, dynamic> data) {
assert(document.firestore == _firestore,
'the document provided is from a different Firestore instance');
return _delegate.update(
document.path, _CodecUtility.replaceValueWithDelegatesInMap(data)!);
}