private function mergeCommitIntoRelease(array $release, array $commitRelease)
    {
        foreach ($commitRelease as $key => $commit) {
            if (!isset($release[$key])) {
                $release[$key] = [
                    'level' => $commit['level'],
                    'messages' => [$commit['message']]
                ];
            } else {
                $release[$key]['messages'][] = $commit['message'];
                $release[$key]['level'] = ($release[$key]['level'] >= $commit['level'])
                    ? $release[$key]['level']
                    : $commit['level'];
            }
        }

        return $release;
    }