Flutter Firebase and Android issue - unable to initialise. Cannot find google-services.json with latest (sept 2020) migration instructions executed

After hours of struggle, I am able to figure out the solution.

1. First, add the 'google-services' plugin as a dependency inside of the android/build.gradle file:

              buildscript {
         dependencies {
           // ... other dependencies
           classpath 'com.google.gms:google-services:4.3.3'
         }
       }
   

2. Lastly, execute the plugin by adding the following underneath the line apply plugin: 'com.android.application', within the /android/app/build.gradle file:

   apply plugin: 'com.google.gms.google-services'
   

Building for Android# Open the /android/app/build.gradle file. Under dependencies add the multidex module, and enable it within the defaultConfig:

        android {
            defaultConfig {
                // ...
                minSdkVersion 16
                targetSdkVersion 28
                multiDexEnabled true
            }
        }

        dependencies {
          implementation 'com.android.support:multidex:1.0.3'
        }

source:https://firebase.flutter.dev/docs/installation/android/