public void persistVehicleTypes() {
   persistIncidents();
   JSONArray jsonVehicleTypes = new JSONArray();
   for (VehicleType vehicleType : vehicleTypes) {
     jsonVehicleTypes.add(vehicleType.jsonify());
   }
   json.put("vehicleTypes", jsonVehicleTypes);
 }
 public VehicleType getVehicleType(int id) {
   for (VehicleType type : vehicleTypes) {
     if (type.getId() == id) {
       return type;
     }
   }
   return null;
 }
 private void restoreVehicleTypes() {
   JSONArray jsonVehicleTypes = (JSONArray) json.get("vehicleTypes");
   int size = jsonVehicleTypes.size();
   for (int i = 0; i < size; ++i) {
     JSONObject jsonVehicleType = (JSONObject) jsonVehicleTypes.get(i);
     VehicleType vehicleType = VehicleType.createFromJSON(jsonVehicleType);
     vehicleTypes.add(vehicleType);
   }
 }