protected function detectChangedFiles(array $pathAndFilenames)
    {
        $changedFiles = [];
        foreach ($pathAndFilenames as $pathAndFilename) {
            $status = $this->changeDetectionStrategy->getFileStatus($pathAndFilename);
            if ($status !== ChangeDetectionStrategyInterface::STATUS_UNCHANGED) {
                $changedFiles[$pathAndFilename] = $status;
            }
        }
        return $changedFiles;
    }