Error in Adding the In-app Billing Library

Question

I was doing this following these steps as mentioned in the link.

1. Copy the IInAppBillingService.aidl file to your Android project.
   (1) If you are

Answer 1

2018

app/build.gradle:

sourceSets {
  main {
    aidl.srcDirs = ['src/main/aidl']
  }
}

or

sourceSets {
  main {
    aidl.srcDirs = ['src']
  }
}

for IInAppBillingService.aidl