I have follow mapping

<class name="c1" table="t1">
<id name="c1_id" unsaved-value="-1">
<generator class="native" />
</id>
<bag name="c2_coll" cascade="all">
<key column="c1_id" />
<one-to-many class="c2"/>
</bag>
</class>

<class name="c2" table="t2">
<id name="c2_id" unsaved-value="-1">
<generator class="native" />
</id>
<many-to-one name="c3_prop" class="c3">
<column name="c3_id"/>
</many-to-one>
</class>

C1 class have collection of C2 classes which have a link( property) to C3 class.
When C3 instance was deleted, and i try load C1 instance - UnresolvableObjectException was thrown.
I have no ideas why not just null. i see it code - it not ajustable with any settings.