private static boolean isRedirected(Map<String, List<String>> header) {
        for (String hv : header.get(null)) {
            if (hv.contains(" 301 ")
                || hv.contains(" 302 ")) {
                return true;
            }
        }
        return false;
    }
synchronized to avoid multiple test threads downloading the same pack concurrently
Don't have to worry about other JVM as this method is called under lock on a single common file.
stroom-test-common/src/main/java/stroom/test/common/util/test/ContentPackZipDownloader.java