Cyclic reference in example Spring bean definition file.

http://xfire.codehaus.org/Spring+Remoting

In the example Spring configuration file at the preceding address, at the end, has a cyclic reference, which causes Spring to fail. The example is as follows:

<bean id="echo" class="org.codehaus.xfire.spring.remoting.XFireExporter">
<property name="serviceFactory">
<ref bean="xfire.serviceFactory"/>
</property>
<property name="xfire">
<ref bean="xfire"/>
</property>
<property name="service">
<ref bean="echo"/>
</property>
<property name="serviceInterface">
<value>org.codehaus.xfire.spring.example.Echo</value>
</property>
</bean>

The bean's id is "echo", and the "service" property references bean "echo". It is my understanding that this is not allowed in Spring. Also, how is the service itself passed to the XFireExporter? It ideally would be configured as a bean, and then passed to the exporter.