add method
Add a DialogModel to the repository, cached
Implementation
@override
Future<DialogModel> add(DialogModel value) {
  return reference.add(value).then((newValue) {
    fullCache[value.documentID] = newValue;
    return newValue;
  });
}Add a DialogModel to the repository, cached
@override
Future<DialogModel> add(DialogModel value) {
  return reference.add(value).then((newValue) {
    fullCache[value.documentID] = newValue;
    return newValue;
  });
}