liquibase-maven-plugin/src/main/java/org/liquibase/maven/plugins/MavenUtils.java
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() + "'");
//    }
  }
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() + "'");
//    }
  }
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.