private static void updateMap(String jar, Map<String,String> packagedClasses) throws IOException {
    if (StringUtils.isEmpty(jar)) {
      return;
    }
    try (ZipFile zip = new ZipFile(jar)){
      for (Enumeration<? extends ZipEntry> iter = zip.entries(); iter.hasMoreElements();) {
        ZipEntry entry = iter.nextElement();
        if (entry.getName().endsWith("class")) {
          packagedClasses.put(entry.getName(), jar);
        }
      }
    }
  }
Add entries to <code>packagedClasses</code> corresponding to class files contained in
<code>jar</code>.

@param jar
         The jar who's content to list.
@param packagedClasses
         map[class -> jar]
ql/src/java/org/apache/hadoop/hive/ql/metadata/JarUtils.java