code: private void setMarkerVisibleInMap(final String id) {
          if (null != id) {
              final WeakReference<MapCoordinateElement> weakReference = mapCoordinateElements.get(id);
              if (null != weakReference) {
                  final MapCoordinateElement mapCoordinateElement = weakReference.get();
                  if (null != mapCoordinateElement) {
                      if (mapCoordinateElement.getVisible()) {
                          jsMapView.call("showMapObject", mapCoordinateElement.getId());
                      } else {
                          jsMapView.call("hideMapObject", mapCoordinateElement.getId());
                      }
                  }
              }
          }
      }
docs: sets the visibility of a MapCoordinateElement in the map.
  
  @param id
  the marker to show or hide