#vulnerable code 
                                @Override
    public Response update(NetworkUpdate networkToUpdate, long id) {
        logger.debug("Network update requested. Id : {}", id);
        networkService.update(id, NetworkUpdate.convert(networkToUpdate));
        logger.debug("Network has been updated successfully. Id : {}", id);
        return ResponseFactory.response(NO_CONTENT);
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public Response update(NetworkUpdate networkToUpdate, long id) {
        logger.debug("Network update requested. Id : {}", id);
        networkService.update(id, networkToUpdate);
        logger.debug("Network has been updated successfully. Id : {}", id);
        return ResponseFactory.response(NO_CONTENT);
    }