Hibernate version:3.2.2.ga and hibernate-annotations 3.3.0.ga

Hello everybody,

I'm trying to define a many-to-many relation using the CaveatEmptor project as a guide but I get a mapping exception. Here is my code:

@Entity
@Table(name="ROLES")
pubic class Role implements Serializable {
...
@ManyToMany
@JoinTable(
name = "ROLE_USER",
joinColumns = {@JoinColumn(name = "ROLE_ID")},
inverseJoinColumns = {@JoinColumn(name = "USER_ID")}
)
public Set<User> users = new HashSet<User>();
public Set<User> getUsers() {
return users;
}
public void setUsers(Set<User> users) {
this.users = users;
}
...
}

@Entity
@Table(name="ROLES")
public class User implements Serializable {
...
@ManyToMany(mappedBy = "users")
public Set<Role> roles = new HashSet<Role>();
public Set<Role> getRoles() {
return roles;
}

public void setRoles(Set<Role> roles){
this.roles = roles;
}
...
}

and I get:
Caused by:
org.hibernate.MappingException: Could not determine type for: java.util.Set, for columns: [org.hibernate.mapping.Column(roles)]
at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:266)
at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:253)
at org.hibernate.mapping.Property.isValid(Property.java:185)
at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:440)
at org.hibernate.mapping.RootClass.validate(RootClass.java:192)
at org.hibernate.cfg.Configuration.validate(Configuration.java:1102)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1287)
at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:915)
at org.springframework.orm.hibernate3.LocalSessionFactoryBean.newSessionFactory(LocalSessionFactoryBean.java:798)
at org.springframework.orm.hibernate3.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:738)
at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.afterPropertiesSet(AbstractSessionFactoryBean.java:131)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1057)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1024)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:421)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:245)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:140)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:242)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:156)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:270)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:346)
at org.springframework.web.context.support.AbstractRefreshableWebApplicationContext.refresh(AbstractRefreshableWebApplicationContext.java:156)
at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:246)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:184)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:49)
at org.mortbay.jetty.servlet.WebApplicationContext.doStart(WebApplicationContext.java:495)
at org.mortbay.util.Container.start(Container.java:72)
at org.mortbay.http.HttpServer.doStart(HttpServer.java:708)
at org.mortbay.util.Container.start(Container.java:72)
at com.iw.plugins.jettyrunner.PluginRunner.launchWithXML(PluginRunner.java:229)
at com.iw.plugins.jettyrunner.PluginRunner.launch(PluginRunner.java:91)
at com.iw.plugins.jettyrunner.PluginRunner.main(PluginRunner.java:75)

But when I move the annotations to the accessor methods everything works fine. Is there something wrong in my code or is this the expected behaviour?
I'm using hiberante 3.2.2.ga and hibernate-annotations 3.3.0.ga.

Any comment will be appreciated,

Thanks
Dragos