Hibernate request for an object based on whether the bound property of the object is null?

I have the following display:

<class name="Customer">
  <!-- actually one-to-one for all intents and purposes-->
  <many-to-one name="specialProperty" class="SpecialProperty" cascade="all" not-found="ignore" insert="false" update="false" column="id" unique="true"/>
</class

<class name="SpecialProperty" lazy="false">
        <id name="id" column="customer_id">
            <generator class="foreign">
                <param name="property">customer</param>
            </generator>
        <one-to-one name="customer" class="Customer" constrained="true"></one-to-one>
</class>

      

        
        
        
      

    

Using this mapping, client.specialProperty is null when there is no entry for a specific client in the special_properties table. (using regular one-to-one matching on the specialProperty containing the proxy so I can't check for null). So in the code, I can just do client.specialProperty == null to see if the Client has a SpecialProperty.

I am trying to write a query that will return all Clients that have a non-null SpecialProperty and another query that will return all Clients that have a null SpecialProperty.

I can get Clients that have a non-null SpecialProperty like:

from Customer customer inner join customer.specialProperty

      

        
        
        
      

    

However, I cannot get clients that do not have a SpecialProperty (e.g. customer.specialProperty == null)

I have tried several things. Basically I want something like

from Customer customer where customer.specialProperty is null

      

        
        
        
      

    

but this generates sql which checks that customer.id is null for whatever reason.

Suggestions?