title: Allowing multiple apps to access one Firebase project through a library
body: <p>I'm trying to build a library allows users to receive Firebase notifications from our server, while still allowing any third-party developer to set and receive their own Firebase notifications. </p>
  
  <p>I'm struggling with how to do this, especially on the console side. I know you have to register your app's applicationID (project name) with the Firebase and then you receive a google-services.json file to add to your app. How does this work with multiple apps with a different package name for each? In my Firebase console, am I continuously adding the project name of each app that uses my library. That doesn't seem right. And how does the google-services.json file handle multiple senders, and which sender generates it?</p>
  
  <p>I'd appreciate any insight from someone with experience in this area.</p>