if (teacher.isResponsibleFor(site.getExecutionCourse()) == null) {
if (! teacher.hasProfessorshipForExecutionCourse(site.getExecutionCourse())) {
    private void checkItem(IUserView remoteUser, Item item) throws NotAuthorizedFilterException {        if (item == null) {            return;        }                Person person = remoteUser.getPerson();                if (person == null) {            throw new NotAuthorizedFilterException();        }                Teacher teacher = person.getTeacher();                if (teacher == null) {            throw new NotAuthorizedFilterException();        }                ExecutionCourseSite site = (ExecutionCourseSite) item.getSection().getSite();        if (teacher.isResponsibleFor(site.getExecutionCourse()) == null) {            throw new NotAuthorizedFilterException();        }    }