This plugin converts the google-services.json file for Firebase into a set of resources that the Firebase libraries can use. It also references the strict-version-matcher plugin, and will execute those checks as well.

Add the following to your project's settings.gradle:

pluginManagement {
    repositories {
        gradlePluginPortal()
        google()
    }
}

Apply the plugin in your app's build.gradle:

plugins {
    id 'com.google.gms.google-services' version '4.2.0'
}

Add the following to your buildscript classpath, obtained from Google’s Maven repository:

classpath 'com.google.gms:google-services:4.2.0'

Apply the plugin in your app's build.gradle:

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

These instructions are also documented online