code: public function loadData(string $section, string &$filename = null)
      {
          $filename = $this->getFilename($section);
  
          if (!file_exists($filename)) {
              return null;
          }
  
          try {
              return include($filename);
          } catch (\Throwable $e) {
              return null;
          }
      }
docs: {@inheritdoc}
  
  @param string $filename Cache filename.