In the Java code, in the JarFile, if the version specified by the property -Djdk.util.jar.version is less than the "base version" (set to 8), it doesn't search for a versioned entry. See the following method (http://hg.openjdk.java.net/jdk9/dev/jdk/file/5c7dda0aa8ce/src/java.base/share/classes/java/util/jar/JarFile.java#l567):

    private ZipEntry getVersionedEntry(ZipEntry ze) {
        ZipEntry vze = null;
        if (BASE_VERSION_MAJOR < versionMajor) {
            String name = ze.getName();
            if (!name.startsWith(META_INF)) {
                vze = searchForVersionedEntry(versionMajor, name);
            }
        }
        return vze == null ? ze : vze;
    }

In the hotspot code, in ClassPathZipEntry::open_versioned_entry(), we have another condition not searching for a versioned entry:
    if (version < base_version || version > cur_ver)
This check should be removed, so that the hotspot code is consistent with the Java code.