public function load($identifier, ParameterBagInterface $parameterBag)
    {
        $stateFilename = $this->getStateFilename($identifier);
        if (!file_exists($stateFilename)) {
            throw new IOException("State file {$stateFilename} doesn't exist!");
        }

        $stateFileContent = file_get_contents($stateFilename);

        $parameterBag->add(unserialize($stateFileContent));
    }