code: @Export
  	public Map createMap(String applicationId, String mapId, String elementId) {
  		Map map = getMap(applicationId, mapId);
  		if (map == null) {
  			MapWidget mapWidget = new MapWidget(mapId, applicationId);
  			map = new MapImpl(mapWidget);
  			Element element = DOM.getElementById(elementId);
  			if (element != null) {
  				int width = element.getClientWidth();
  				int height = element.getClientHeight();
  				map.setSize(width, height);
  				map.setHtmlElementId(elementId);
  			}
  			registerMap(mapId, applicationId, map);
  		} else {
  			((MapImpl) map).getMapWidget().redraw();
  		}
  		return map;
  	}
docs: Register the given {@link Map} with applicationId and mapId.
  
  @param applicationId
  the application id.
  @param mapId
  the map id.
  @param elementId
  the DOM element ID onto which to attach the map.