To get lazy loading working on nullable one-to-one mappings you need to let hibernate do compile time instrumentation and add a @LazyToOne(value = LazyToOneOption.NO_PROXY)
to the one-to-one relation.
Example Mapping:
@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name="other_entity_fk")
@LazyToOne(value = LazyToOneOption.NO_PROXY)
public OtherEntity getOther()
Example Ant Build file extension (for doing the Hibernate compile time instrumentation):
<property name="src" value="/your/src/directory"/><!-- path of the source files -->
<property name="libs" value="/your/libs/directory"/><!-- path of your libraries -->
<property name="destination" value="/your/build/directory"/><!-- path of your build directory -->
<fileset id="applibs" dir="${libs}">
<include name="hibernate3.jar" />
<!-- include any other libraries you'll need here -->
</fileset>
<target name="compile">
<javac srcdir="${src}" destdir="${destination}" debug="yes">
<classpath>
<fileset refid="applibs"/>
</classpath>
</javac>
</target>
<target name="instrument" depends="compile">
<taskdef name="instrument" classname="org.hibernate.tool.instrument.javassist.InstrumentTask">
<classpath>
<fileset refid="applibs"/>
</classpath>
</taskdef>
<instrument verbose="true">
<fileset dir="${destination}">
<!-- substitute the package where you keep your domain objs -->
<include name="/com/mycompany/domainobjects/*.class"/>
</fileset>
</instrument>
</target>