eZ\Publish\Core\Helper\ContentPreviewHelper::getOriginalSiteAccess PHP Method

    public function getOriginalSiteAccess()
    {
        return $this->originalSiteAccess;
    }

 /**
  * @throws NotImplementedException If Content is missing location as this is not supported in current version
  */
 public function previewContentAction(Request $request, $contentId, $versionNo, $language, $siteAccessName = null)
 {
     $this->previewHelper->setPreviewActive(true);
     try {
         $content = $this->contentService->loadContent($contentId, array($language), $versionNo);
         $location = $this->locationProvider->loadMainLocation($contentId);
         if (!$location instanceof Location) {
             throw new NotImplementedException("Preview for content without locations");
         }
         $this->previewHelper->setPreviewedContent($content);
         $this->previewHelper->setPreviewedLocation($location);
     } catch (UnauthorizedException $e) {
         throw new AccessDeniedException();
     }
     if (!$this->authorizationChecker->isGranted(new AuthorizationAttribute('content', 'versionread', array('valueObject' => $content)))) {
         throw new AccessDeniedException();
     }
     $siteAccess = $this->previewHelper->getOriginalSiteAccess();
     // Only switch if $siteAccessName is set and different from original
     if ($siteAccessName !== null && $siteAccessName !== $siteAccess->name) {
         $siteAccess = $this->previewHelper->changeConfigScope($siteAccessName);
     }
     $response = $this->kernel->handle($this->getForwardRequest($location, $content, $siteAccess, $request), HttpKernelInterface::SUB_REQUEST);
     $response->headers->remove('cache-control');
     $response->headers->remove('expires');
     $this->previewHelper->restoreConfigScope();
     $this->previewHelper->setPreviewActive(false);
     return $response;
 }