Description :
i want to know how can we write a component with composite-id, for example the following documents mapping...
[b]Hibernate version:
2.1.6
Mapping documents:
Bar.hbm.xml :
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping package="filters">

<class name="test.Bar" table="BAR">

<composite-id>
<key-property name="nom" column="nom" type="int" />
<key-property name="prenom" column="prenom" type="int" />
<key-many-to-one name="id" class="test.Foo" column="CODE_FOO"/>
</composite-id>
<property name="email" type="string" column="email" />
</class>

</hibernate-mapping>

Foo.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping package="filters">

<class name="test.Foo" table="Foo">
<id
name="id"
type="int"
column="CODE_FOO">
<generator class="native"/>
</id>
<property
name="nom"
column="NAME"
type="string"
/>

</class>

</hibernate-mapping>

Code between sessionFactory.openSession() and session.close():

Full stack trace of any exception that occurs:
Buildfile: C:\java\eclipse\workspace\test\build.xml
codegen:
[hbm2java] Processing 2 files.
[hbm2java] Building hibernate objects
[hbm2java] 21:25:13,484 WARN BasicRenderer:404 - No properties has been marked as being used in equals/hashcode for Bar. Using object identifier which is RARELY safe to use! See http://hibernate.org/109.html
BUILD SUCCESSFUL
Total time: 1 second
Name and version of the database you are using:

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

Check the docs:
http://www.hibernate.org/hib_docs/reference/en/html/toolsetguide.html#toolsetguide-s2

The warning is telling you to use HBM meta tags to indicate the properties that should be used in the equals and hashcode methods that are required to be generated. See tag implement-equals and use-in-equals.