public function setSubMerchant(string $mchId, string $appId = null)
    {
        $this['config']->set('sub_mch_id', $mchId);
        $this['config']->set('sub_appid', $appId);

        return $this;
    }
public function setSubMerchant(string $mchId, string $appId = null)
    {
        $this['config']->set('sub_mch_id', $mchId);
        $this['config']->set('sub_appid', $appId);

        return $this;
    }
public function setSubMerchant ( string $ mchId , string $ appId = null ) { $ this [ 'config' ] -> set ( 'sub_mch_id' , $ mchId ) ; $ this [ 'config' ] -> set ( 'sub_appid' , $ appId ) ; return $ this ; }
Set sub-merchant.

@param string      $mchId
@param string|null $appId

@return $this
Set sub - merchant .