My database object are setup as follows

MainUser extends OnlineUser
OnlineUser extends OnlineUser


where OnlineUser can have many property.

Mapping documents:
I got following two mappings
for user obj;
Java Code:
  <subclass discriminator-value="O" name="com.wf.core.OnlineUser"> 
  <subclass discriminator-value="M" name="com.wf.core.MainUser"> 
  <subclass discriminator-value="T" name="com.wf.core.TopicUser"> 
where classes are define as follows ;
Java Code:
public class OnlineUser extends User {} 
public class MainUser extends MainUser{} 
public class TopicUser extends OnlineUser {}

then i got a property obj;
Java Code:
<many-to-one class="com.wf.core.User" name="user" not-null="true"> 
      <column name="property_user"/> 

The issue is,
i want to list the properties that belong to Topic User, how do i generate the Criteria for that.

so far..
Java Code:
Criteria crit = wf.getSession().createCriteria( 
now how do i check if property is belong to TopicUser, not MainUser or User?