handleMessage method
Implementation
@override
void handleMessage(
    MapViewController mapViewController, Map<String, dynamic> payload) {
  mapViewController._usingViewerNavigation = true;
  SitumSdk().updateNavigationState(payload);
}@override
void handleMessage(
    MapViewController mapViewController, Map<String, dynamic> payload) {
  mapViewController._usingViewerNavigation = true;
  SitumSdk().updateNavigationState(payload);
}