public static function manyToMany($modelClass, $connection, $options = []) {
        $options['type'] = self::MANY_TO_MANY;
        $options['modelClass'] = $modelClass;
        $connection = explode('(', $connection);
        $table = $connection[0];
        list($c1, $c2) = explode(',', $connection[1]);
        $r = new self($options);
        $c1 = trim($c1);
        $c2 = trim($c2);
        $r->join(trim($table), [["t.__PK__", "j.$c1", "="]])
            ->compare(["j.$c2" => "r." . $modelClass::getDb()->getTablePk($modelClass::getTableName())]);
        return $r;
    }