code: public static boolean isRegistered(URL url) {
  
  		if (url == null) {
  			throw new IllegalArgumentException("Camera device URL cannot be null");
  		}
  
  		try {
  			return isRegistered(url.toURI());
  		} catch (URISyntaxException e) {
  			throw new WebcamException(e);
  		}
  	}
docs: Is device with given URL registered?
  
  @param url the URL used by device
  @return True if device is registered, false otherwise