* Appends WMS tiled image layer configuration elements to the superclass configuration document.
   * @param params configuration parameters describing this WMS tiled image layer.
   * @return a WMS tiled image layer configuration document.
  protected Document createConfigurationDocument(AVList params) {

    Document doc = super.createConfigurationDocument(params);
    if (doc == null || doc.getDocumentElement() == null) return doc;

    LayerConfiguration.createWMSTiledImageLayerElements(params, doc.getDocumentElement());

    return doc;
  protected static AVList wmsGetParamsFromDocument(Element domElement, AVList params) {
    if (domElement == null) {
      String message = Logging.getMessage("nullValue.DocumentIsNull");
      throw new IllegalArgumentException(message);

    if (params == null) params = new AVListImpl();

    LayerConfiguration.getWMSTiledImageLayerParams(domElement, params);
    BasicTiledImageLayer.getParamsFromDocument(domElement, params);

    params.setValue(AVKey.TILE_URL_BUILDER, new URLBuilder(params));

    return params;