title: How to provide GoogleSignInOptions using Dagger2?
body: <p>I am trying to make small Firebase login app using Dagger2, but I have a problem with GoogleSignInOptions. I want to set it in the AppModule, but .requestIdToken have an error with:
  (getString(R.string.default_web_client_id))
  Is my approach with GoogleSignInOptions appropriate? Maybe it's the wrong way? Sorry for that, but I am little confused about injection of the Firebase stuff. </p>
  
  <pre><code>@Module
  class AppModule {
  
  @Provides
  fun getApp(application: Application?): Boolean {
      return application == null
  }
  
  @Singleton
  @Provides
  fun provideFirebaseAuthInstance(): FirebaseAuth {
      return FirebaseAuth.getInstance()
  }
  
  @Singleton
  @Provides
  fun provideGoogleSignInClient() : GoogleSignInOptions {
  
     return GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
          .requestIdToken(getString(R.string.default_web_client_id)) //here is a problem
          .requestEmail()
          .build()
  }
  
  }
  </code></pre>