基于相关实体属性是否为null，实体的Hibernate查询？

I have the following mapping:

我有以下映射:

<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>
<clas