/** Map publicid to a resource accessible by a classloader. */
    public void registerCatalogEntry(String publicId, String resourceName, ClassLoader loader) {
      if (id2resource == null) id2resource = new Hashtable(17);
      id2resource.put(publicId, resourceName);

      if (loader != null) {
        if (id2loader == null) id2loader = new Hashtable(17);
        id2loader.put(publicId, loader);
      }
    }
 public void registerCatalogEntry(String publicId, String uri) {
   if (id2uri == null) id2uri = new Hashtable(17);
   id2uri.put(publicId, uri);
 }