public class InstructionLine implements Serializable {

       private Integer id;
       private Integer item;
   private Collection<InstructionLine> parents;// this is to be saved in instruction_hierarchy
   private Collection<InstructionLine> children;// this is to be saved in instruction_hierarchy

        ----getter and setter----------
}

<hibernate-mapping package="com.brainscript.tangram.sales.despatchorder.domain.impl">
   <class name="BaseDespatchOrderLines" table="inventory.despatch_order_lines">
      
      <id   name="id" column="id" unsaved-value="null">
         <generator class="sequence">
            <param name="sequence">inventory.instruction_lines_id_seq</param>
         </generator>
      </id>

      <property name="comments" column="comments"/>
      <property name="item" column="item_id"/>   
      
      
   //Is this possible
   <!--   <bag name="children" cascade="all-delete-orphan" lazy="false" table="inventory.instruction_hierarchy">
         <key column="id" not-null="true"/>
         <one-to-many class="com.brainscript.tangram.sales.salesorder.domain.impl.InstructionLine"/>
      </bag>-->


   </class>
   
   
   
   
   
</hibernate-mapping>