title: Fluent NHibernate, joined-subclass mapping
body: <p>I'm trying to map a joined-subclass scenario using Fluent NHibernate.
  I have a class Entity defined in the namespace Core, and a class
  SubClass : Entity in the namespace SomeModule</p>
  
  <p>Now I obviously don't want class Entity to know about its derived
  types, the SomeModules namespace references Core - not the other way
  around.</p>
  
  <p>All the examples I've been able to find use something like:</p>
  
  <pre><code>public class EntityMap : ClassMap&lt;Entity&gt; {
      public EntityMap() {
          Id(x =&gt; x.Id)
  
          var subClassMap = JoinedSubClass&lt;SubClass&gt;("SubClassId", sub =&gt; sub.Map(x =&gt; x.Id));
  
          subClassMap.Map(x =&gt; x.SomeProperty)
          ...
      }
  }
  </code></pre>
  
  <p>This simply won't work in my situation - I need something akin to the
  NHibernate xml mapping:</p>
  
  <pre><code>&lt;joined-subclass name="SubClass" extends="Entity, Core" &gt;
  &lt;key column="SubClassId" foreign-key="FK_KollegiumEntity"/&gt;
  &lt;property name="Name" length="255" not-null="true" /&gt;
  ...
  &lt;/joined-subclass&gt;
  </code></pre>
  
  <p>Has anyone achieved this with Fluent NHibernate?</p>