Make course section import multi-threaded

    public void importCourseSection(Map<String, Map<String, List<CourseSection>>> sections) {

        CourseService courseService = serviceFactory.createService(CourseService.class);

        for (var courseEntry : sections.entrySet()) {

            for (var semesterEntry : courseEntry.getValue().entrySet()) {

                for (var section : semesterEntry.getValue()) {

                    sectionIdMap.put(section.id, courseService.addCourseSection(courseEntry.getKey(),

                            mapSemesterId(Integer.parseInt(semesterEntry.getKey())),

                            section.name, section.totalCapacity));

                }

            }

        }

        sections.entrySet().parallelStream().forEach(courses -> {

            String courseId = courses.getKey();

            courses.getValue().entrySet().parallelStream().forEach(semester -> {

                int semesterId = mapSemesterId(Integer.parseInt(semester.getKey()));

                semester.getValue().parallelStream().forEach(section ->

                        sectionIdMap.put(section.id, courseService.addCourseSection(courseId, semesterId,

                                section.name, section.totalCapacity))

                );

            });

        });

    }

    public void importCourseSectionClasses(Map<String, List<CourseSectionClass>> classes) {