app purchase for custom market?

hi i use unreal 4.15 and i want to add market for app purchase. for use this market i use sample code,and in his code say use IInAppBillingService.aidl file and folder util i check this and i find same in my intermediate folder of my project only thing that has different between is in class IabHelper in line 265 and 266 now
i found way to change this class but when use blueprint always purchase failed.any way to use custom market?