throw new DomainException(this.getClass().getName(), "errors.notExisting.studentInGroupig");
throw new DomainException(this.getClass().getName(), "errors.notExisting.studentInGrouping");
    private void checkForStudentsInStudentGroupsAndGrouping(List<IStudent> students) {        for (IStudent student : students) {            IAttends attend = getStudentAttend(student);            for (final IStudentGroup studentGroup : this.getStudentGroups()) {                if (studentGroup.getAttends().contains(attend))                    throw new DomainException(this.getClass().getName(), "errors.existing.studentEnrolment");                                else if(!this.getAttends().contains(attend))                    throw new DomainException(this.getClass().getName(), "errors.notExisting.studentInGroupig");            }        }    }