code: private void updateChargingStationAvailability(ChargingStationId chargingStationId, Availability availability) {
          ChargingStation chargingStation = repository.findOne(chargingStationId.getId());
  
          if (chargingStation != null) {
              chargingStation.setAvailability(availability);
              repository.createOrUpdate(chargingStation);
          }
      }
docs: Updates the charging station's availability.
  
  @param chargingStationId the charging station's id.
  @param availability      the charging station's new availability.