private void areAllStatesReachable() {
   areNbInitialFinalStatesValid();
   if (validationInput != null) {
     validationInput.reach();
   }
   for (State s : Diagram.getInstance().getAllStates()) {
     if (!s.isReach()) {
       this.addError(new DiagramError("State unreachable : " + s.toString()));
       isValid = false;
     }
   }
   for (State s : Diagram.getInstance().getAllStates()) {
     s.setReach(false);
     s.setAlreadyTest(false);
   }
 }