/** read from plugin registry and parse it. */
  public void readRegistry(String extensionPointId) {
    IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();
    IExtensionPoint point = extensionRegistry.getExtensionPoint(PLUGIN_ID, extensionPointId);

    if (point != null) {
      IConfigurationElement[] elements = point.getConfigurationElements();
      for (int i = 0; i < elements.length; i++) {
        readElement(elements[i]);
      }
    }
  }