title: How do use Property(string notVisiblePropertyOrFieldName, Action<IPropertyMapper> mapping) for ComposedId?
body: <p>I'm trying to map something in code.</p>
  
  <p>this works fine:</p>
  
  <pre><code>ComposedId(cm =&gt;
                 {
                     cm.Property(x =&gt; x.Column1);
                     cm.Property(x =&gt; x.Column2);
                 });
  </code></pre>
  
  <p>which is function</p>
  
  <pre><code>void Property&lt;TProperty&gt;(Expression&lt;Func&lt;TContainer, TProperty&gt;&gt; property);
  </code></pre>
  
  <p>However, I'm trying to make it more dynamic, with</p>
  
  <pre><code>void Property(string notVisiblePropertyOrFieldName, Action&lt;IPropertyMapper&gt; mapping)
  </code></pre>
  
  <p>I tried setting about every option, like so:</p>
  
  <pre><code>ComposedId(cm =&gt;
                 {
                         cm.Property("Column1", a =&gt;
                                                     {
                                                         a.Access(Accessor.Property);
                                                         a.Column("Column1");
                                                         a.Generated(PropertyGeneration.Never);
                                                         a.Index("Column1");
                                                         a.Insert(true);
                                                         a.Lazy(false);
                                                         a.NotNullable(true);
                                                         a.Update(true);
                                                         a.Unique(false);
                                                         a.Type(NHibernateUtil.Int32);
                                                         a.Length(int.MaxValue);
                                                         a.Scale(0);
                                                     });
                     }
                 });
  </code></pre>
  
  <p>And similar for Column2, but nothing seems to work.
  it simply ignores my ComposedId, I assume nhibernate does not recognize it as a proper identifier, because it tries to an "Id" column as identifier, which does not exist.</p>
  
  <p>how am I suppose to create the Action mapping so that it does work?</p>