One of my apps was recently removed from Google Play because they found that I was collecting ANDROID_ID, aka the Android ID advertising identifier without a privacy policy. I was using it for something trivial, so I removed it from the code, and re-submitted. It was approved but then later taken down again for the same reason.
They are now telling me that my app is collecting and using the advertising identifier through https://app-measurement.com/a. Clearly, it is being used in one of the libraries I am using as part of my build. Searching the project in Android Studio for "android_id" or app-measurement comes up with nothing relevant.
How can I find the uses of android_id in the project for myself and figure out what part of my code (what library) is to blame?