looks like the set-method did the trick
<mapping>
<class-a>org.apache.camel.converter.dozer.service.Customer</class-a>
<class-b bean-factory="org.apache.camel.converter.dozer.model.CustomerBeanFactory">org.apache.camel.converter.dozer.model.Customer
</class-b>
<field>
<a>street</a>
<b set-method="setStreet">address.street</b>
</field>
</mapping>