public class UnresolvableObjectExceptionTest {

   private static final Logger logger = Logger.getLogger(UnresolvableObjectExceptionTest.class);

   static SessionFactory sessionFactory;

   public static void main(String[] args) throws Exception {
      UnresolvableObjectExceptionTest tester = new UnresolvableObjectExceptionTest();
      tester.setUp();
      tester.testUnresolvableObjectExceptionTest();
   }
   
   private void setUp() throws Exception {
      Session session = getSession();
      Transaction tx = session.beginTransaction();
      
      B b1 = new B();
      b1.setId(new Long(1));
      b1.setB1("b1.B1");
      session.save(b1);
      
      C c1 = new C();
      CKey ckey = new CKey();
      ckey.setA3("a1.A3");
      ckey.setA4("a1.A4");
      c1.setCKey(ckey);
      c1.setC1("c1.C1");
      session.save(c1);
      
      A a1 = new A();
      a1.setA1(new Long(1234));
      a1.setA3("a1.A3");
      a1.setA4("a1.A4");
      a1.setB(b1);
      a1.setC(c1);
      session.save(a1);
      
      
      tx.commit();
      session.close();
      
      
   }

   public void testUnresolvableObjectExceptionTest() throws Exception {

      Session session = getSession();

      logger.info("Test Starting.........");
      String sql = "from A as a left join fetch a.c where a.a1 = :a1";
      Query query = session.createQuery(sql);
      query.setParameter("a1", new Long(1234));
      List list = query.list();
      for (Iterator i = list.iterator(); i.hasNext();) {
         A a = (A) i.next();
         System.out.println(a.getA1() + " " + a.getA3() + " " + a.getA4());
      }
      logger.info("Test Completed Successfully");
   }

   private Session getSession() throws Exception {

      if (sessionFactory == null) {
         Configuration cfg = new Configuration()
         .addResource("test/uoe/Mapping.hbm.xml")
         .setProperty("hibernate.connection.driver_class","org.hsqldb.jdbcDriver")
         .setProperty("hibernate.connection.url", "jdbc:hsqldb:.")
         .setProperty("hibernate.dialect", "net.sf.hibernate.dialect.HSQLDialect")
         .setProperty("hibernate.connection.username", "sa")
         .setProperty("hibernate.connection.password", "")
         .setProperty("hibernate.connection.autocommit", "false")
         .setProperty("hibernate.show_sql", "true")
         .setProperty("hibernate.hbm2ddl.auto", "create-drop");

         sessionFactory = cfg.buildSessionFactory();
      }
      return sessionFactory.openSession();
   }
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping package="test.uoe" >
  <class name="A" table="A" mutable="false">
    <id name="a1" column="A1" type="java.lang.Long">
      <generator class="assigned"/>
    </id>
    <many-to-one class="B" name="b" column="A2" not-null="false" outer-join="false" insert="false"/>
    <property name="a3" column="A3" type="string" />
    <property name="a4" column="A4" type="string" />       
    <many-to-one class="C" name="c" not-null="false" outer-join="true" insert="false" update="false">
      <column name="A3"/>
      <column name="A4" />
    </many-to-one>
  </class>
 
  <class name="B" table="b">
    <id name="id" column="A2" type="java.lang.Long">
      <generator class="assigned"/>
    </id>
    <property name="b1" column="B1" type="string"/>
  </class>
  <class name="C" table="c">
    <composite-id class="CKey" name="CKey">
      <key-property name="a3" column="A3" type="string"/>
      <key-property name="a4" column="A4" type="string"/>
    </composite-id>
    <property name="c1" column="C1" type="string"/>
  </class>
</hibernate-mapping>