ExternalLink::getDefaultPreFilters

protected function getDefaultPreFilters()
{
	$defaultPreFilters = parent::getDefaultPreFilters();

	$defaultPreFilters[] = function(Event $event) {
		/** @var ClosureWrapper $this */
		$currentUser = CurrentUser::get();
		foreach ($this->getAction()->getArguments() as $argument)
		{
			if (!($argument instanceof DiskExternalLink))
			{
				continue;
			}

			if ($argument->getCreatedBy() != $currentUser->getId())
			{
				$this->errorCollection[] = new Error(
					Loc::getMessage('Could not operate with external link of stranger')
				);

				return new EventResult(EventResult::ERROR, null, null, $this);
			}
		}
	};

	return $defaultPreFilters;
}