code: public static String getSmallLayerIconUrl(Layer<?> layer) {
  		ClientExtraLayerInfo eli = (ClientExtraLayerInfo) layer.getLayerInfo().getWidgetInfo(
  				ClientExtraLayerInfo.IDENTIFIER);
  		if (eli != null && eli.getSmallLayerIconUrl() != null && !"".equals(eli.getSmallLayerIconUrl())) {
  			return eli.getSmallLayerIconUrl();
  		} else {
  			return null;
  		}
  	}
docs: Get small layer image URL.
  
  @param layer
  layer
  @return image URL