code: public final ReadOnlyObjectProperty<LatLongBounds> boundsProperty() {
          if (bounds == null) {
              bounds = new ReadOnlyObjectWrapper<>(getBounds());
              addStateEventHandler(MapStateEventType.idle, () -> {
                  bounds.set(getBounds());
              });
          }
          return bounds.getReadOnlyProperty();
      }
docs: A property tied to the map, updated when the idle state event is fired.
  
  @return