public function findByCollection($collection, $version = null)
    {
        if ($collection instanceof Collection) {
            $collection = $collection->getCollectionID();
        }

        $criteria = [
            'collection_id' => $collection
        ];

        if ($version && $version instanceof Version) {
            $version = $version->getVersionID();
        }

        if ($version) {
            $criteria['collection_version_id'] = $version;
        }

        return $this->findBy($criteria);
    }