comments-bundle/src/Resources/contao/dca/tl_comments.php
public function invalidateSourceCacheTag(Contao\DataContainer $dc, array $tags)
	{
		$commentModel = Contao\CommentsModel::findByPk($dc->id);

		if (null !== $commentModel)
		{
			$tags[] = sprintf('contao.comments.%s.%s', $commentModel->source, $commentModel->parent);
		}

		return $tags;
	}
public function invalidateSourceCacheTag(Contao\DataContainer $dc, array $tags)
	{
		$commentModel = Contao\CommentsModel::findByPk($dc->id);

		if (null !== $commentModel)
		{
			$tags[] = sprintf('contao.comments.%s.%s', $commentModel->source, $commentModel->parent);
		}

		return $tags;
	}
Adds the cache invalidation tags for the source.

@param Contao\DataContainer $dc
@param array                $tags

@return array