public async Task <ActionResult <IEnumerable <LectureWithCourseResource> > > GetAllLectures()
        {
            var lectures = await _lectureService.GetAllLecturesWithCourse().ToListAsync();

            var lecturesResource = _mapper.Map <IEnumerable <Lecture>, IEnumerable <LectureWithCourseResource> >(lectures);

            return(Ok(lecturesResource));
        }