Problem with SaveCustomerAttribute

Hello.

I'm  upgrade from 2.50 to 2.80. I have a plugin, it´s work fine in version 2.50, but when recompiled in version 2.80 give me this error.
'Nop.Services.Customers.ICustomerService' does not contain a definition for 'SaveCustomerAttribute' and no extension method 'SaveCustomerAttribute' accepting a first argument of type 'Nop.Services.Customers.ICustomerService' could be found (are you missing a using directive or an assembly reference?)

this is the conflict line.
_customerService.SaveCustomerAttribute<string>(customer, string.Format(ORDERPAYMENTCARDTYPE, postProcessPaymentRequest.Order.Id), product);

thanks

Attributes are now persisted generically.  Example:

\src\Libraries\Nop.Services\Customers\CustomerExtentions.cs

            genericAttributeService.SaveAttribute(customer, SystemCustomerAttributeNames.GiftCardCouponCodes, result);

Thank's New York.
I saw that class yesterday.
i'm testing today.

Thanks.