Why I am getting this error? This is the portion of my daoImpl Im calling

```
@Transactional
@Repository
public class PersonDaoImpl implements PersonDao{

    @Autowired
    private SessionFactory sessionFactory;

    @SuppressWarnings("unchecked")
    @Override
    @Transactional(readOnly=true)
    public List<Person> getAllPersons(){
        List<Person> persons = (List<Person>) sessionFactory.getCurrentSession()
            .createCriteria(Person.class)
            .setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY)
            .list();
        return persons;
    }

```

Portion of my person model

```
@OneToMany(fetch = FetchType.LAZY, mappedBy = "person", cascade = CascadeType.ALL)
    private Set<Contact> contacts;

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "PERSON_ROLE", joinColumns = {
            @JoinColumn(name = "person_id", nullable = false, updatable = false) }, 
            inverseJoinColumns = { @JoinColumn(name = "role_id", 
                    nullable = false, updatable = false) })
    private Set<Role> roles = new HashSet<Role>(0);

```

In my service impl, I convert model to dto using `BeanUtils`
What am I doing wrong?