eZ\Publish\Core\Repository\ContentService::publishVersion PHP Method

    public function publishVersion(APIVersionInfo $versionInfo)
    {
        $content = $this->internalLoadContent($versionInfo->contentInfo->id, null, $versionInfo->versionNo);
        if (!$content->getVersionInfo()->getContentInfo()->published) {
            if (!$this->repository->canUser('content', 'create', $content)) {
                throw new UnauthorizedException('content', 'create', array('contentId' => $content->id));
            }
        } elseif (!$this->repository->canUser('content', 'edit', $content)) {
            throw new UnauthorizedException('content', 'edit', array('contentId' => $content->id));
        }
        $this->repository->beginTransaction();
        try {
            $content = $this->internalPublishVersion($content->getVersionInfo());
            $this->repository->commit();
        } catch (Exception $e) {
            $this->repository->rollback();
            throw $e;
        }
        return $content;
    }