<class name="nl.strohalm.cyclos.entities.accounts.Account" table="accounts" discriminator-value="account">
      <id name="id" type="long" column="account_id">
            <generator class="native"/>
      </id>
      <discriminator column="subclass" type="string"/>

      <property name="creationDate" column="creationDate" type="calendar"/>
      <property name="lastAmount" column="lastAmount" type="float"/>

      <many-to-one name="owner" column="owner_id" class="nl.strohalm.cyclos.entities.accounts.IAccountOwner"/>
      
      <subclass name="nl.strohalm.cyclos.entities.accounts.LimitedAccount" discriminator-value="limited_account"/>
</class>

<class name="nl.strohalm.cyclos.entities.accounts.IAccountOwner" table="members">
        <id name="id" type="long" column="member_id">
            <generator class="native"/>
        </id>
        <discriminator column="subclass" type="string"/>
    <subclass name="nl.strohalm.cyclos.entities.application.Application" discriminator-value="application">
        <one-to-one name="bankAccount" class="nl.strohalm.cyclos.entities.accounts.Account" property-ref="owner"/>
        <one-to-one name="communityAccount" class="nl.strohalm.cyclos.entities.accounts.LimitedAccount" property-ref="owner"/>
    </subclass>
</class>

[schemaexport] BUILD FAILED: file:/home/igor/workspace/cyclos/build.xml:92: Schema text failed: property-ref not found: owner in class: nl.strohalm.cyclos.entities.accounts.LimitedAccount

public class Account {

   private Long id;
   private Calendar creationDate;
   public IAccountOwner owner;
..............

public class LimitedAccount extends Account {

   public LimitedAccount() throws ApplicationException {
      super();
   }

   public LimitedAccount(IAccountOwner owner) throws ApplicationException {
      super(owner);
   }
}