// Create a jar file, specifying a Main-Class
final String jarFileName = "um-existence.jar";
new File(jarFileName).delete(); // remove pre-existing first!
Main jartool = new Main(out, err, "jar");
boolean status = jartool.run(
new String[] { "cfe", jarFileName, "Hello", existence.getPath() });
check(status);
checkManifest(jarFileName, "Hello");
// Update that jar file by changing the Main-Class