dispose method

@override @protected @mustCallSuper void dispose()

Discards any resources used by the object. After this is called, the object is not in a usable state and should be discarded (calls to addListener and removeListener will throw after the object is disposed).

This method should only be called by the object's owner.

Implementation

@override
@protected
@mustCallSuper
void dispose() {
  super.dispose();
  RuntimeDatabase._db.removeDocumentListener(_query);
}