How to add a marker tap/click on map using Flutter/Dart?

The plugin has finally added an onTap property for the GoogleMap Class.

final ArgumentCallback<LatLng> onTap

Example:

GoogleMap(
    markers: _markers,
    initialCameraPosition: _theSecretLocation,
    onMapCreated: (GoogleMapController controller) {
      _controller.complete(controller);
    },
    onTap: _handleTap,
  ),
  ...

 _handleTap(LatLng point) {
setState(() {
  _markers.add(Marker(
    markerId: MarkerId(point.toString()),
    position: point,
    infoWindow: InfoWindow(
      title: 'I am a marker',
    ),
    icon:
        BitmapDescriptor.defaultMarkerWithHue(BitmapDescriptor.hueMagenta),
  ));
});
}