Use MLKit Barcode scanner from a module other the app module

Question

This is a confusing problem, I've tried to use ML-kits barcode scanner to detect QR codes, if I place the dependency implementation 'com.google.mlkit:barcode-scanning:17.2.0' in the app level Build.gradle the reader works fine. If i ty to add that in my module level build.gradle then the application crashes by citing com.google.android.gms.common.api.optionalmoduleapi class is not found. What may the issue?

I've tried adding the dependency as api from the app module, this works but I cannot do that because it'll use more space. This app also has an instant app. so the total size of the app cannot exceed 15MB as per the documentation.