<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.integration.core">
   <class name="ModelElement" table="model_element">
      <id name="uuid" type="string" column="uuid">
         <generator class="uuid"/>
      </id>
      <discriminator column="type" type="string"/>
      <property name="name" column="name" type="string" not-null="true"/>
      <property name="created" column="created" type="timestamp" update="false" not-null="true"/>
      <property name="stereotype" column="stereotype" type="string" not-null="true"/>
      <property name="description" column="description" type="string" not-null="false"/>
      <set name="attachments" table="attachment" lazy="true">
         <key column="uuid"/>
         <one-to-many class="com.integration.model.Attachment"/>
      </set>
      <many-to-one name="parent" class="ModelElement" access="property" cascade="save-update, persist, merge">
         <column name="parent_uuid" not-null="false"/>
      </many-to-one>
      <set name="childElements" access="property" cascade="all" inverse="true">
         <key column="parent_uuid"/>
         <one-to-many class="ModelElement"/>
      </set>
      <set name="associationsA" table="association" lazy="true">
         <key column="uuidA"/>
         <one-to-many class="com.integration.model.associations.Association"/>
      </set>
      <set name="associationsB" table="association" lazy="true">
         <key column="uuidB"/>
         <one-to-many class="com.integration.model.associations.Association"/>
      </set>
      <set name="designDecisions" table="modelElement_designDecision" lazy="true" cascade="save-update">
         <key column="model_element_id"/>
         <many-to-many class="com.integration.model.DesignDecision" column="design_decision_id"/>
      </set>
<subclass name="com.integration.model.Task" discriminator-value="task">
         <set name="issues" table="issue" inverse="true">
                  <key column="task_uuid"/>
                  <one-to-many class="com.integration.model.Issue"/>
         </set>
         <join table="task">
            <key column="uuid"/>
               <property name="assignedTo" column="assigned_to" type="string" not-null="true"/>
               <property name="priority" column="priority" type="string" not-null="true"/>
               <property name="percentCompleted" column="percent_completed" type="string" not-null="true"/>
               <property name="estimatedEffort" column="estimated_effort" type="string" not-null="true"/>
               <property name="executedEffort" column="executed_effort" type="string" not-null="true"/>
               <property name="status" column="status" type="string" not-null="true"/>
               <property name="initialDate" column="initial_date" type="string" not-null="true"/>
               <property name="finishDate" column="finish_date" type="string" not-null="true"/>
         </join>
      </subclass>
      <subclass name="com.integration.model.Issue" discriminator-value="issue">
         <join table="issue" fetch="select">
            <key column="uuid"/>
               <property name="impact" column="impact" type="string" not-null="true"/>
               <property name="openingDate" column="opening_date" type="string" not-null="true"/>
               <property name="commitmentDate" column="commitment_date" type="string" not-null="true"/>
               <property name="closingDate" column="closing_date" type="string" not-null="true"/>
               <property name="assignedTo" column="assigned_to" type="string" not-null="true"/>
               <property name="status" column="status" type="string" not-null="true"/>
               <property name="criticity" column="criticity" type="string" not-null="true"/>
               <many-to-one name="task" class="com.integration.model.Task" column="task_uuid"/>
         </join>
      </subclass>
</class>
</hibernate-mapping>

Task task = (Task)hsession.get(Task.class, "402880e60714fbbd010714fc6a2d0001");
            System.out.println("ASSIGNED TO: " +task.getAssignedTo());
            System.out.println("ISSUES.SIZE: " +task.getIssues().size());