Is there a way to insert a row in join tables only if all the properties in the table is not-null. I'm already using optional="true" in the join for the tables but Hibernate seems to be inserting even when a property for the join is null.

Mapping file
--------------

<class name="com.app.user" table="user">

<id name="id" column="user_id">
<generator class="sequence"><param name="sequence">seq_user_id_seq</param></generator>
</id>

<property name="login" column="login" type="string" not-null="true" unique="true"/>
<property name="password" column="password" type="string" not-null="true"/>
<property name="firstName" column="first_name" type="string"/>

<join table="cs_user" optional="true">
<key column="user_id"/>
<property name="csCreatedBy" column="created_by" type="long" not-null="true"/>
<property name="csCreatedOn" column="created_on" type="timestamp"/>
</join>

<join table="ut_user" optional="true">
<key column="user_id"/>
<property name="utCreatedBy" column="created_by" type="long" not-null="true"/>
<property name="utCreatedOn" column="created_on" type="timestamp"/>
</join>

</class>

What I would like to achieve is don't insert a row for the join if a property for example utCreatedOn is null. It seems that the 'optional' attribute is not doing that although according to the documentation it should be. Thanks.