code: private static void addArtifact(Set<URI> urls,
                                    Artifact artifact,
                                    Log log,
                                    boolean verbose)
            throws MalformedURLException {
      File f = artifact.getFile();
      if (f == null) {
        log.warn("Artifact with no actual file, '" + artifact.getGroupId()
                 + ":" + artifact.getArtifactId() + "'");
      } else {
        addFile(urls, f, log, verbose);
      }
  //    if (f != null) {
  //      URL fileURL = f.toURI().toURL();
  //      if (verbose) {
  //        log.info("  artifact: " + fileURL);
  //      }
  //      urls.add(fileURL);
  //    } else {
  //      log.warning("Artifact with no actual file, '" + artifact.getGroupId()
  //               + ":" + artifact.getArtifactId() + "'");
  //    }
    }
docs: Adds the artifact file into the set of URLs so it can be used in a URLClassLoader.
  @param urls The set to add the artifact file URL to.
  @param artifact The Artifact to resolve the file for.
  @throws MalformedURLException If there is a problem creating the URL for the file.