private static function purgeImageAliasForObject( array $cacheItem, eZContentObject $object, array $imageIdentifiers )
    {
        $versions = $object->attribute( 'versions' );
        foreach ( $versions as $version )
        {
            $dataMap = $version->attribute( 'data_map' );
            foreach ( $imageIdentifiers as $identifier )
            {
                $attr = $dataMap[$identifier];
                if ( !$attr instanceof eZContentObjectAttribute )
                {
                    eZDebug::writeError( "Missing attribute $identifier in object " . $object->attribute( 'id' ) . ", version " . $version->attribute( 'version' ) . ". This indicates data corruption.", __METHOD__ );
                }
                elseif ( $attr->attribute( 'has_content' ) )
                {
                    $attr->attribute( 'content' )->purgeAllAliases();
                }
            }
        }
    }