Dependency for SMS Retriever API

I am trying to implement SMS Retriever API, but I am unable to find classes like SmsRetrieverClient. I'm not able to import them.

Refer to the following sample code:

 SmsRetrieverClient client = SmsRetriever.getClient(context);
 Task<Void> task = client.startSmsRetriever();
 task.addOnSuccessListener(new OnSuccessListener<Void>() {});

I have added following dependency, after which I am able to refer the classes:

compile 'com.google.android.gms:play-services:11.0.2'

1. But as this include all service API, I want to know the dependency specific to SMS Retriever API

   I have referred to this doc for all dependency and added following, but it did not work.

   com.google.android.gms:play-services-auth:11.0.2
   com.google.android.gms:play-services-identity:11.0.2
   

2. Also, is it necessary to have 11.x.x versions?