@Test
   public void save() {
      Job job = new Job();
      ...
      job.addCategory( categoryDao.find( 1 ) );

      jobDao.save( job );
      clear();

      assertFalse( job.isTransient() );

      jdbcMap = simpleJdbcTemplate.queryForMap( "select * from job where job_id = ?", job.getId() );
      ... // test stuff

      // Spring FAILS here - it cannot find 1 row.
      jdbcMap = simpleJdbcTemplate.queryForMap( "select * from job_to_category where job_id = ?", job.getId() );
      assertEquals( 1, jdbcMap.get( "CATEGORY_ID" ) );
   }

<hibernate-mapping default-access="field" auto-import="true" default-lazy="true" default-cascade="all-delete-orphan">

    <class name="myproject.domain.job.Job" table="job">
        <id name="id" column="job_id" type="long">
            <generator class="native"/>
        </id>
        <property name="positionName" column="position_name"/>
        <property name="description" type="text"/>
        <property name="excerpt" type="text"/>
        <property name="googleMapUrl" column="google_map_url"/>
        <property name="expiryDate" column="expiry_date"
                  type="org.joda.time.contrib.hibernate.PersistentLocalDate" />
        <property name="views"/>
        <bag name="categories" table="job_to_category">
            <key column="job_id" />
            <many-to-many class="myproject.domain.Category" column="category_id" />
        </bag>
    </class>

    <class name="myproject.domain.Category" table="category">
        <id name="id" column="category_id" type="long">
            <generator class="native"/>
        </id>
        <property name="name" column="name"/>
        <many-to-one name="parent" class="myproject.domain.Category"
                     column="parent_id"/>
        <set name="children" inverse="true">
            <key column="category_id"/>
            <one-to-many class="myproject.domain.Category"/>
        </set>
    </class>

</hibernate-mapping>