Running Junit5 Test in scr/test/java from main

in my project i want run methods(with annotation @Test) in classes in src/test/java that are contained in a jar (this jar contain also test classes). My code for run test method is this:

public class ServiceUtil {
   Launcher launcher = LauncherFactory.create();
   ClassLoader loader = URLClassLoader.newInstance(
                new URL[]{new File("C:\\User\\Giuseppe\\test_path"+ "\\" + jar).toURI().toURL()},   //in Unix usare "/"
                ServiceUtil.class.getClassLoader()
        );
   Class cls = loader.loadClass("MyTestClass");
   Constructor constructor = cls.getConstructor();
   Object o = constructor.newInstance();
   LauncherDiscoveryRequest request;
   if (o!=null) {
       cls=o.getClass();
       Method m=o.getClass().getMethod("MyMethodTest".get());
       request = LauncherDiscoveryRequestBuilder.request()
                 .selectors(selectMethod(cls, m))
                 .build();
        }
    TestPlan testPlan = launcher.discover(request);
    LOGGER.info("containTest? "+testPlan.containsTests()+"");  <----IS FALSE!!!!
    launcher.registerTestExecutionListeners(listener);
    launcher.execute(request);
}

Tests are not executed because no valid test methods are detected (infact testPlan.containsTests() is False) but i dont view ERROR!

Some tips for this "stange error?"

Is possible execute JUNIT5 Test from external?

Thanks Regards