if (!modelDao.hasModel(modelId)) {
throw new ObjectNotFoundException("Model not found", modelId); //$NON-NLS-1$
}
SecurityModel securityModel = modelDao.getSecurityModel(modelId);
Collection<Role> roles = EcoreUtil.getObjectsByType(securityModel.getEClassifiers(), UamPackage.eINSTANCE.getRole());
TreeSet<Role> set = new TreeSet<Role>(new RoleComparator());
set.addAll(roles);
return set;
}