Permission permission = new Permission( "test permission " + uniqueLongValue() );
        Set s = new HashSet();
        s.add( permission );
        assertTrue(s.contains( permission ));
        session.save( permission );
        commitTransactionCloseAndReopenSession();
       
        Permission retrievedPermission = (Permission )session.get(Permission.class, permission.getId());
        assertEquals(permission.hashcode(), retrievedPermission.hashcode());
       
        assertEquals(permission, retrievedPermission);
        assertEquals(retrievedPermission, permission);
       
        assertFalse(permission == retrievedPermission);
       
        assertTrue(s.contains( permission ));
        assertTrue(s.contains( retrievedPermission ));   

import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.commons.collections.set.UnmodifiableSet;
import org.hibernate.HibernateException;

import com. .ime.context.IMEContext;
import com. .ime.exception.IMEErrorCode;
import com. .ime.exception.IMEException;

/**
* @hibernate.class table="PERMISSION"
* @hibernate.discriminator column="PERMISSION_TYPE" type="java.lang.String"
*
* @hibernate.query name="findAllPermissions" query="from Permission p"
*
* @hibernate.query name="findPermissionByValue" query="from Permission p where
*                  p.value = :value"
* 
*/
public abstract class AbstractPermission
{

    public static final String ID = "permissionID";
    public static final String PERMISSION = "permission";
    public static final String PERMISSIONS = "permissions";

    private String value;
    private Long id;


    protected AbstractPermission()
    {
    }

    protected AbstractPermission( String value )
    {
        setValue( value );
    }

    /**
     * @hibernate.property column = "value" unique = "true" not-null = "true"
     *                     length="255"
     * @return value
     */
    protected String getValue()
    {
        return this.value;
    }

    private void setValue( String value )
    {
        this.value = value;
    }


    /**
     * @hibernate.id generator-class="native" column = "PERMISSION_ID" name="id"
     * @return id
     */
    public Long getId()
    {
        return this.id;
    }

    private void setId( Long id )
    {
        this.id = id;
    }

    public String toString()
    {
        return getValue();
    }

    public boolean equals( Object o )
    {
        if( o == null )
        {
            return false;
        }
        if( o == this )
        {
            return true;
        }
        if( !(o instanceof AbstractPermission) )
        {
            return false;
        }
        return ((AbstractPermission)o).getValue().equals( this.getValue() );
    }

    public int hashcode()
    {
        int result = 17;
        result = result * 37 + getValue().hashCode();
        return result;
    }


}


/**
* @hibernate.subclass table="PERMISSION" discriminator-value="userpermission"
* 
*/
public class Permission extends AbstractPermission
{
    public static final Permission USER_PERMISSION_1 = new Permission( "UserPermission1" );


    protected Permission()
    {

    }

    protected Permission( String value )
    {
        super( value );
    }

}

<?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
>
    <class
        name="com. .ime.domain.user.AbstractPermission"
        table="PERMISSION"
        dynamic-update="false"
        dynamic-insert="false"
        select-before-update="false"
        optimistic-lock="version"
    >

        <id
            name="id"
            column="PERMISSION_ID"
            type="java.lang.Long"
        >
            <generator class="native">
              <!-- 
                  To add non XDoclet generator parameters, create a file named
                  hibernate-generator-params-AbstractPermission.xml
                  containing the additional parameters and place it in your merge dir.
              -->
            </generator>
        </id>

        <discriminator
            column="PERMISSION_TYPE"
            type="java.lang.String"
        />

        <property
            name="value"
            type="java.lang.String"
            update="true"
            insert="true"
            access="property"
            column="value"
            length="255"
            not-null="true"
            unique="true"
        />

        <!--
            To add non XDoclet property mappings, create a file named
                hibernate-properties-AbstractPermission.xml
            containing the additional properties and place it in your merge dir.
        -->
        <subclass
            name="com. .ime.domain.user.Permission"
            dynamic-update="false"
            dynamic-insert="false"
            discriminator-value="userpermission"
        >
       <!--
               To add non XDoclet property mappings, create a file named
                hibernate-properties-Permission.xml
      containing the additional properties and place it in your merge dir.
       -->

        </subclass>
        <subclass
            name="com. .ime.domain.user.AdminPermission"
            dynamic-update="false"
            dynamic-insert="false"
            discriminator-value="adminpermission"
        >
       <!--
               To add non XDoclet property mappings, create a file named
                hibernate-properties-AdminPermission.xml
      containing the additional properties and place it in your merge dir.
       -->

        </subclass>

    </class>

        <query name="findAllPermissions"><![CDATA[
            from Permission p
        ]]></query>
        <query name="findPermissionByValue"><![CDATA[
            from Permission p where p.value = :value
        ]]></query>

</hibernate-mapping>

//
//where coll2 is a persistent set and item is a transient entity
//
System.out.println("Coll2:  " + coll2.getClass().getName());
System.out.println("Coll2 contains item:  " + coll2.contains(item));
Set hashSet = new HashSet(coll2);
System.out.println("HashSet contains item:  " + hashSet.contains(item));

//output
Coll2:  org.hibernate.collection.PersistentSet
Coll2 contains item:  false
HashSet contains item:  true