public class Job<ID, T> {
}

public class EntityKey {
}

public interface IJobApi<ID, T> {
	Optional<Job<ID, T>> findJob(@NotNull ID jobId);
}

public class JobApi implements IJobApi<UUID, EntityKey> {
	public Optional<Job<UUID, EntityKey>> findJob(UUID jobId) {
		return null;
	}
}

@Test
public void parameter_validation_works_for_generic_method_with_optional_return_value() throws Exception {
	Method method =  JobApi.class.getDeclaredMethod( "findJob", UUID.class );
	Object[] values = new Object[] { null };
	Set<ConstraintViolation<JobApi>> constraintViolations = validator
			.forExecutables()
			.validateParameters( new JobApi(), method, values);
	assertNumberOfViolations( constraintViolations, 1 );
	assertCorrectPropertyPaths( constraintViolations, "findJob.arg0" );
	assertCorrectConstraintViolationMessages( constraintViolations, "may not be null" );
}