/**
  * Convert a sequence of URIs to URLs.
  *
  * @param uris the uris to convert
  * @return the corresponding urls
  * @exception IOException of a transformation error occurs
  */
 public static URL[] toURLs(URI[] uris) throws IOException {
   URL[] urls = new URL[uris.length];
   for (int i = 0; i < urls.length; i++) {
     URI uri = uris[i];
     if (Artifact.isRecognized(uri)) {
       urls[i] = Artifact.toURL(uri);
     } else {
       urls[i] = uri.toURL();
     }
   }
   return urls;
 }