FluidTYPO3\Flux\Core::getRegisteredProviderExtensionKeys PHP Method

    public static function getRegisteredProviderExtensionKeys($forControllerName)
    {
        if (TRUE === isset(self::$extensions[$forControllerName])) {
            return array_unique(array_merge(self::$extensions[self::CONTROLLER_ALL], self::$extensions[$forControllerName]));
        }
        return self::$extensions[self::CONTROLLER_ALL];
    }

 /**
  * Gets a collection of path configurations for content elements
  * based on each root TypoScript template in the provided array
  * of templates. Returns an array of paths indexed by the root
  * page UID.
  *
  * @param array $templates
  * @return array
  */
 protected function getPathConfigurationsFromRootTypoScriptTemplates($templates)
 {
     $allTemplatePaths = array();
     $registeredExtensionKeys = Core::getRegisteredProviderExtensionKeys('Content');
     foreach ($templates as $templateRecord) {
         $pageUid = $templateRecord['pid'];
         /** @var \TYPO3\CMS\Core\TypoScript\ExtendedTemplateService $template */
         $template = GeneralUtility::makeInstance('TYPO3\\CMS\\Core\\TypoScript\\ExtendedTemplateService');
         $template->tt_track = 0;
         $template->init();
         /** @var \TYPO3\CMS\Frontend\Page\PageRepository $sys_page */
         $sys_page = GeneralUtility::makeInstance('TYPO3\\CMS\\Frontend\\Page\\PageRepository');
         $rootLine = $sys_page->getRootLine($pageUid);
         $template->runThroughTemplates($rootLine);
         $template->generateConfig();
         $oldTemplatePathLocation = (array) $template->setup['plugin.']['tx_fed.']['fce.'];
         $newTemplatePathLocation = (array) $template->setup['plugin.']['tx_fluidcontent.']['collections.'];
         $registeredPathCollections = array();
         foreach ($registeredExtensionKeys as $registeredExtensionKey) {
             $nativeViewLocation = $this->getContentConfiguration($registeredExtensionKey);
             if (FALSE === isset($nativeViewLocation['extensionKey'])) {
                 $nativeViewLocation['extensionKey'] = ExtensionNamingUtility::getExtensionKey($registeredExtensionKey);
             }
             $registeredPathCollections[$registeredExtensionKey] = $nativeViewLocation;
         }
         $merged = GeneralUtility::array_merge_recursive_overrule($oldTemplatePathLocation, $newTemplatePathLocation);
         $merged = GeneralUtility::removeDotsFromTS($merged);
         $merged = GeneralUtility::array_merge($merged, $registeredPathCollections);
         $allTemplatePaths[$pageUid] = $merged;
     }
     return $allTemplatePaths;
 }