title: How to update marker position google maps flutter
body: <p>I want to use a custom marker as user position. I am listening to location event and on each move I want to set new lat/lon on this marker. However I don't see any options to update markers position. How can I achieve this? I've tried removing the current marker and adding a new one, but there's ugly flash effect which I do not want.</p>
  <pre class="lang-dart prettyprint-override"><code>  final marker = Marker(
          markerId: MarkerId('1'),
          position: LatLng(_latitude, _longitude),
          icon: await customIcon()
      );
  
      setState(() {
        _markers.add(marker);
      });
      _location.onLocationChanged.listen((event) async {
        //here I want to update the marker lat lng with new event.latitude and event.longitude
      });
  </code></pre>