code: private void setReservable(ChargingStationId chargingStationId, boolean reservable) {
          ChargingStation chargingStation = repository.findOne(chargingStationId.getId());
  
          if (chargingStation != null) {
              chargingStation.setReservable(reservable);
              repository.createOrUpdate(chargingStation);
          }
      }
docs: Makes a charging station reservable or not reservable.
  
  @param chargingStationId the charging station to make reservable or not reservable.
  @param reservable        true if reservable, false if not.