title: Create index on column in one-to-many relationship
body: <p>I have a one-to-many relationship between two classes like this:</p>
  
  <pre><code>class Parent {
      List&lt;Child&gt; children;
  }
  
  class Child {
      String name;
  }
  </code></pre>
  
  <p>I'm using an <code>.hbm.xml</code> file to define my mapping from Java classes to tables. Something like this:</p>
  
  <pre><code>&lt;class name="Parent" table="parent"&gt;
      &lt;list name="children"&gt;
          &lt;key column="parent_id" /&gt;
          &lt;list-index column="idx" /&gt;
          &lt;one-to-many class="Child" /&gt;
      &lt;/list&gt;
  &lt;/class&gt;
  
  &lt;class name="Child" table="child"&gt;
      &lt;property name="name" type="string" /&gt;
  &lt;/class&gt;
  </code></pre>
  
  <p>That works fine.</p>
  
  <p>Now I want to create a column index (not a list index) on the <code>Child.parent_id</code> column. It seems that the <code>&lt;one-to-many&gt;</code> tag doesn't allow any nested <code>&lt;column&gt;</code> tags, so I tried adding a bidirectional association to the <code>Child</code> mapping like this:</p>
  
  <pre><code>&lt;many-to-one name="parent" insert="false" update="false"&gt;
      &lt;column name="parent_id" index="true"&gt;
  &lt;/many-to-one&gt;
  </code></pre>
  
  <p>But I get an exception: </p>
  
  <pre><code> org.hibernate.PropertyNotFoundException: Could not find a getter for parent in class Child
  </code></pre>
  
  <p>So, how can I create an index on the <code>Child.parent_id</code> column without adding a <code>parent</code> field to the <code>Child</code> class? I'm using Hibernate 3.5.6 and PostgreSQL 9.3.</p>