Hibernate 3 null exception, join fetch query

Question

I have an issue with a search query.

My model:

Project:

@Entity
@Table(name = "project")
public class Project {

    @Id
    @Column(name = "id")
    @GeneratedValue
    private Integer id;

    @ManyToMany(fetch=FetchType.EAGER)
    @JoinTable(
        name="project_tag",
        joinColumns = @JoinColumn(name="project_id"),
        inverseJoinColumns = @JoinColumn(name="tag_id")
    )
    private Set<Tag> requiredSkills;

    @Column(name="name")
    private String name;

    @Column(name = "short_description", columnDefinition="TEXT")
    private String shortdescription;

    @Column(name = "extended_description", columnDefinition="TEXT")
    private String extendedDescription;
}

Tag:

@Entity
@Table(name="tag", uniqueConstraints = {@UniqueConstraint(columnNames={"name"})})
public class Tag {

    @Id
    @Column(name = "id")
    @GeneratedValue
    private Integer id;

    @Column(name = "name")
    private String name;

    public int hashCode() {
        return getName().hashCode();
    }
}

I want to search projects with some search string, and I want to find projects with this string in the name, short description, extended description, AND tags. Searching for tags is the problem.

Here is my query:

public List<Project> search(String search) {
        search = "%" + search + "%";
        Query query = sessionFactory.getCurrentSession().createQuery(
                "from Project p" +
                " left join fetch p.requiredSkills r" +
                " where p.name like :search" +
                " or p.shortdescription like :search" +
                " or p.extendedDescription like :search" +
                " or r.name like :search"
                );
        query.setParameter("search", search);

        query.setMaxResults(30);

        return (List<Project>) query.list();
    }

The line "or r.name like :search" is giving me an error (everything works fine without it):

java.lang.NullPointerException
    myProject.model.Tag.hashCode(Tag.java:53)

I get this error only when some projects are found (no error when no results returned). Any ideas? Thanks!

Edit: forgot to tell that projects may have 0 to n tags...