public function file_list()
 {
     return $this->directory_items->getFiles();
 }
 private function createForbiddenDirectoryContents()
 {
     $parent_item = new DirectoryItem('..', 'dir', null, null);
     $directory_contents = new DirectoryItemCollection(array($parent_item), array());
     $directory_contents->setAsForbidden();
     return $directory_contents;
 }