Add app purchase of another market of android

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

problem is when copy sample file to intermediate folder and i build project this file overwriting and dont usable for my app
how to access this class and use it in unreal or visual studio?