title: StreamProvider not updating List
body: <p>I have a StreamController which should update a <code>List</code> but it doesn't happen:</p>
  
  <pre class="lang-dart prettyprint-override"><code>class LocationService {
      StreamController&lt;List&lt;bg.Geofence&gt;&gt; geofencesController = StreamController&lt;List&lt;bg.Geofence&gt;&gt;();
  
      updateGeofences(geofences) {
          logger.i('listing geofences $geofences');
          geofencesController.add(List.from(list));
      }
  }
  </code></pre>
  
  <p>When I call <code>updateGeofences</code> I got many geofences in logs. 
  But widget are not rebuilt!</p>
  
  <p>Here is my providers setup:</p>
  
  <pre class="lang-dart prettyprint-override"><code>class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return MultiProvider(
          providers: [
            StreamProvider&lt;List&lt;bg.Geofence&gt;&gt;.value(
                updateShouldNotify: (_, __) {
                  logger.i('updateShouldNotify, $_, $__');
                  return true;
                },
                initialData: List&lt;bg.Geofence&gt;(),
                stream: LocationService().geofencesController.stream)
          ],
          child: MaterialApp()
       );
    }
  }
  
  </code></pre>
  
  <p>When I listen directly from my service with</p>
  
  <pre class="lang-dart prettyprint-override"><code>geofencesController.stream.listen((onData) {
    logger.i('Got eem! $onData');
  });
  </code></pre>
  
  <p>The streams emits new data...
  But not in the StreamProvider: <code>updateShouldNotify</code> is never called (I tried without luck this <a href="https://stackoverflow.com/questions/57365207/streamprovider-not-updating-state">answer's</a> solutions)</p>
  
  <p>Here is how I get my data in view:</p>
  
  <pre class="lang-dart prettyprint-override"><code>class GPSView extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      List&lt;bg.Geofence&gt; geofences = Provider.of&lt;List&lt;bg.Geofence&gt;&gt;(context);
  
  </code></pre>
  
  <p>But this list remains empty.</p>
  
  <p>I have another StreamController with a simple Map which works perfectly. What's wrong?</p>