RESOLU :
The line
private ArrayList<Fiche> fiches = new ArrayList<Fiche>();
has been replaced by:
private List<Fiche> fiches = new ArrayList<Fiche>();
and it works now.
That's it.




Hibernate version:
hibernate-3.2.0.cr2
hibernate-annotations-3.2.0.CR1.zip
jdk 1.5.0_08

Mapping documents:
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import javax.persistence.Basic;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.Enumerated;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

import org.hibernate.annotations.IndexColumn;


@Entity
public class Individu implements Serializable {

/**
*
*/
private static final long serialVersionUID = -4782256312700340494L;
public static enum Sexe { MASCULIN, FEMININ };

private Long id;
private String nomComplet;
private String nom;
private String prenom;
private Date dateDeNaissance;
private String lieuNaissance;
private Sexe sexe = Sexe.MASCULIN;
private ArrayList<Fiche> fiches = new ArrayList<Fiche>();
/**
* @param id the id to set
*/
public void setId(Long id) {
this.id = id;
}
/**
* @return the id
*/
@Id @GeneratedValue(strategy=GenerationType.AUTO)
public Long getId() {
return id;
}
/**
* @param nomComplet the nomComplet to set
*/
public void setNomComplet(String nomComplet) {
this.nomComplet = nomComplet;
}
/**
* @return the nomComplet
*/
@Basic
public String getNomComplet() {
return nomComplet;
}
/**
* @param nom the nom to set
*/
public void setNom(String nom) {
this.nom = nom;
}
/**
* @return the nom
*/
@Basic
public String getNom() {
return nom;
}
/**
* @param dateDeNaissance the dateDeNaissance to set
*/
public void setDateDeNaissance(Date dateDeNaissance) {
this.dateDeNaissance = dateDeNaissance;
}
/**
* @return the dateDeNaissance
*/
@Temporal(TemporalType.DATE)
public Date getDateDeNaissance() {
return dateDeNaissance;
}
/**
* @param lieuNaissance the lieuNaissance to set
*/
public void setLieuNaissance(String lieuNaissance) {
this.lieuNaissance = lieuNaissance;
}
/**
* @return the lieuNaissance
*/
@Basic
public String getLieuNaissance() {
return lieuNaissance;
}
/**
* @param sexe the sexe to set
*/
public void setSexe(Sexe sexe) {
this.sexe = sexe;
}
/**
* @return the sexe
*/
@Enumerated
public Sexe getSexe() {
return sexe;
}
/**
* @param fiches the fiches to set
*/
public void setFiches(ArrayList<Fiche> fiches) {
this.fiches = fiches;
}
/**
* @return the fiches
*/
@OneToMany(cascade=CascadeType.ALL)
@IndexColumn(name="fiche")
@OrderBy("fiche")
public List<Fiche> getFiches() {
return fiches;
}

}

/** Le code et les annotations de la class fiche maintenant */
@Entity
public class Fiche implements Serializable {
/**
*
*/
private static final long serialVersionUID = 4576138465945556591L;

private Long fiche;

/** Date de validité de la fiche */
private Date date;
/** Profession */
private String profession;
private boolean refFonction = false;
/** Suppléant */
private Individu suppleant = null;



/**
* @param fiche the fiche to set
*/
public void setFiche(Long fiche) {
this.fiche = fiche;
}
/**
* @return the fiche
*/
@Id @GeneratedValue(strategy=GenerationType.AUTO)
public Long getFiche() {
return fiche;
}
/**
* @param profession the profession to set
*/
public void setProfession(String profession) {
this.profession = profession;
}
/**
* @return the profession
*/
@Basic
public String getProfession() {
return profession;
}
/**
* @param suppleant the suppleant to set
*/
public void setSuppleant(Individu suppleant) {
this.suppleant = suppleant;
}
/**
* @return the suppleant
*/
@OneToOne
public Individu getSuppleant() {
return suppleant;
}
/**
* @param date the date to set
*/
public void setDate(Date date) {
this.date = date;
}
/**
* @return the date
*/
@Temporal(TemporalType.DATE)
public Date getDate() {
return date;
}
/**
* @param apparente the apparente to set
*/
public void setApparente(boolean apparente) {
this.apparente = apparente;
}
/**
* @return the apparente
*/
@Basic
public boolean isApparente() {
return apparente;
}

/**
* @param refFonction the refFonction to set
*/
public void setRefFonction(boolean refFonction) {
this.refFonction = refFonction;
}
/**
* @return the refFonction
*/
@Basic
public boolean isRefFonction() {
return refFonction;
}


}

ANT task definition
<path id="toolslib">
<path location="${lib.dir}/hibernate-tools.jar" />
<path location="${lib.dir}/hibernate3.jar" />
<path location="${lib.dir}/freemarker.jar" />
<path location="${lib.dir}/commons-logging-1.0.4.jar" />
<path location="${mysql-connector.jar}" />
<fileset dir="${lib.dir}/">
<include name="*.jar"/>
</fileset>
<pathelement location="${jars}/meteopol.jar"/>
<pathelement location="${bin}/"/>
</path>


<taskdef name="hibernatetool" classname="org.hibernate.tool.ant.HibernateToolTask" classpathref="toolslib" />


<target name="schema">
<hibernatetool destdir="${hib.dir}">
<annotationconfiguration configurationfile="${hib.dir}/hibernate.cfg.xml"/>
<classpath >
<path location="${build.dir}" />
</classpath >
<!-- list exporters here -->
<hbm2ddl create="true" update="true" export="true" outputfilename="sql.ddl" format="true" />
<hbm2doc/>
</hibernatetool>
</target>


Code between sessionFactory.openSession() and session.close():
Session session = HibernateUtil.getSession();
session.beginTransaction();
Individu ind = new Individu();
ind.setNom("Foo");
ind.setDateDeNaissance(new java.util.Date());
session.save(ind);
session.getTransaction().commit();

Full stack trace of any exception that occurs:
Exception in thread "main" org.hibernate.PropertyAccessException: IllegalArgumentException occurred while calling setter of semiosys.meteopo
l.wrappers.Individu.fiches
at org.hibernate.property.BasicPropertyAccessor$BasicSetter.set(BasicPropertyAccessor.java:104)
at org.hibernate.tuple.AbstractEntityTuplizer.setPropertyValues(AbstractEntityTuplizer.java:330)
at org.hibernate.tuple.PojoEntityTuplizer.setPropertyValues(PojoEntityTuplizer.java:191)
at org.hibernate.persister.entity.AbstractEntityPersister.setPropertyValues(AbstractEntityPersister.java:3343)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:272)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:180)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:108)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186
)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:537)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:525)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:521)
at semiosys.meteopol.control.Starter.main(Starter.java:28)
Caused by: java.lang.IllegalArgumentException: argument type mismatch
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.hibernate.property.BasicPropertyAccessor$BasicSetter.set(BasicPropertyAccessor.java:42)
... 15 more


Name and version of the database you are using:
MySQL 5.021 COmmunity edition


Commentaire
On a simplement un objet <Individu> qui peut contenir sous la forme d'une liste des <Fiche>s.
L'exception arrive dès que session.save(objet) est appelé.
Il me semble pourtant que les annotations sont correctement définies.