I am working on a project that contains multiple Java modules. Implementing new Firebase Crashlytics went fine with main Application module, and I get crash reports in Firebase console, but I can't get it to work with these other library modules. The only thing similar to the problem I have is in this Fabric docs link, but even dough Google bought them, it doesn't work with Firebase version of Crashlytics.
Like all other Firebase SDKs, Firebase Crashlytics depends on a Firebase configuration that can only be applied to your application module. You can't apply Firebase configuration to a library module. You can put the Crashlytics dependency in a library module, but you still need to configure the app module so the SDK knows where to report the errors it captures. This involves google-services.json and applying the fabric.io plugin, as described in the documentation.