addListener method
Adds a listener to this repository
listener
is called when there is a change in some model in repositoryMap
and you set the property to notify in the function.
This serves to keep the controllers that make use of the models in this repository notified
and has the same data. (Only if this repositoru is used in multiple controllers)
Implementation
void addListener(Function(List<RepoUpdate<Id>>) listener) {
_repositoryStream.stream.listen(listener);
}