public Participation(int id, String date_part, int etat, String notif, Payaiment payaiment)
 {
     this.id        = id;
     this.date_part = date_part;
     this.notif     = notif;
     this.payaiment = payaiment;
 }
 public Participation(int id, String date_part, int etat, String notif, Payaiment payaiment, Participant participant, Activite activite)
 {
     this.id          = id;
     this.date_part   = date_part;
     this.notif       = notif;
     this.payaiment   = payaiment;
     this.participant = participant;
     this.activite    = activite;
 }