google-services plugin could not detect any version for com.google.android.gms or com.google.firebase, default version: 9.0.0 will be used

Question

I am integrating fire-base to my existing project used these libs

   compile 'com.google.firebase:firebase-auth:9.0.2'
compile 'com.google.firebase:firebase-database:9.0.2'
compile 'com.google.android.gms:play-services:9.0.2'

Dependencies

    dependencies {
    classpath 'com.android.tools.build:gradle:2.1.2'
    classpath 'com.google.gms:google-services:3.0.0'
    // NOTE: Do not place your application dependencies here; they belong
    // in the individual module build.gradle files
}

I am getting this error

Error:Execution failed for task ':app:processDebugGoogleServices'.

Please fix the version conflict either by updating the version of the google-services plugin (information about the latest version is available at https://bintray.com/android/android-tools/com.google.gms.google-services/) or updating the version of com.google.android.gms to 9.0.0.

Not able to figure out what is happening ??

These are my play services verison

Answer 1

I have added this line at last in build.gradle:(Module: app)

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

and it started working I don't know what is concept behind this?
but it is working