private static String readExportHeader(String jarFile) throws IOException {
        try (JarInputStream jar = new JarInputStream(new FileInputStream(jarFile))) {
            return jar.getManifest().getMainAttributes().getValue(Constants.EXPORT_PACKAGE);
        }
    }
@author Simon Thoresen Hult
@author gjoranv
jdisc_core/src/main/java/com/yahoo/jdisc/core/ExportPackages.java