StudentGroup studentGroup = FenixFramework.getDomainObject(studentGroupCode);
if (studentGroup == null) {
throw new FenixServiceException();
}
GroupEnrolmentStrategyFactory enrolmentGroupPolicyStrategyFactory = GroupEnrolmentStrategyFactory.getInstance();
IGroupEnrolmentStrategy strategy = enrolmentGroupPolicyStrategyFactory.getGroupEnrolmentStrategyInstance(groupProperties);
if (!strategy.checkStudentInGrouping(groupProperties, username)) {
throw new NotAuthorizedException();
}