Non-nullable return

packages/extension_google_sign_in_as_googleapis_auth/README.md

@@ -19,19 +19,19 @@ That object can then be used to create instances of `googleapis` API clients:
 
 <?code-excerpt "example/lib/main.dart (CreateAPIClient)"?>
 ```dart
-// Retrieve an [auth.AuthClient] from the current [GoogleSignIn] instance.
-final auth.AuthClient? client = await _googleSignIn.authenticatedClient();
-
-assert(client != null, 'Authenticated client missing!');
-
-// Prepare a People Service authenticated client.
-final PeopleServiceApi peopleApi = PeopleServiceApi(client!);
-// Retrieve a list of the `names` of my `connections`
-final ListConnectionsResponse response =
-    await peopleApi.people.connections.list(
-  'people/me',
-  personFields: 'names',
-);
+import 'package:googleapis_auth/googleapis_auth.dart' as auth show AuthClient;
+// ···
+    // Retrieve an [auth.AuthClient] from a GoogleSignInClientAuthorization.
+    final auth.AuthClient client = authorization.authClient(scopes: scopes);
+
+    // Prepare a People Service authenticated client.
+    final PeopleServiceApi peopleApi = PeopleServiceApi(client);
+    // Retrieve a list of connected contacts' names.
+    final ListConnectionsResponse response =
+        await peopleApi.people.connections.list(
+      'people/me',
+      personFields: 'names',
+    );
 ```
 
 ## Example

packages/extension_google_sign_in_as_googleapis_auth/example/lib/main.dart

@@ -10,9 +10,9 @@ import 'package:extension_google_sign_in_as_googleapis_auth/extension_google_sig
 import 'package:flutter/material.dart';
 import 'package:google_sign_in/google_sign_in.dart';
 import 'package:googleapis/people/v1.dart';
-// #docregion Import
+// #docregion CreateAPIClient
 import 'package:googleapis_auth/googleapis_auth.dart' as auth show AuthClient;
-// #enddocregion Import
+// #enddocregion CreateAPIClient
 
 /// The scopes used by this example.
 const List<String> scopes = <String>[PeopleServiceApi.contactsReadonlyScope];
@@ -79,7 +79,7 @@ class SignInDemoState extends State<SignInDemo> {
     });
 
     if (authorization != null) {
-      unawaited(_handleGetContact());
+      unawaited(_handleGetContact(authorization));
     }
   }
 
@@ -93,19 +93,18 @@ class SignInDemoState extends State<SignInDemo> {
         .authorizeScopes(<String>[PeopleServiceApi.contactsReadonlyScope]));
   }
 
-  Future<void> _handleGetContact() async {
+  Future<void> _handleGetContact(
+      GoogleSignInClientAuthorization authorization) async {
     setState(() {
       _contactText = 'Loading contact info...';
     });
 
     // #docregion CreateAPIClient
     // Retrieve an [auth.AuthClient] from a GoogleSignInClientAuthorization.
-    final auth.AuthClient? client = _authorization?.authClient(scopes: scopes);
-
-    assert(client != null, 'Authenticated client missing!');
+    final auth.AuthClient client = authorization.authClient(scopes: scopes);
 
     // Prepare a People Service authenticated client.
-    final PeopleServiceApi peopleApi = PeopleServiceApi(client!);
+    final PeopleServiceApi peopleApi = PeopleServiceApi(client);
     // Retrieve a list of connected contacts' names.
     final ListConnectionsResponse response =
         await peopleApi.people.connections.list(
@@ -154,6 +153,7 @@ class SignInDemoState extends State<SignInDemo> {
         future: _signInInitialized,
         builder: (BuildContext context, AsyncSnapshot<void> snapshot) {
           final GoogleSignInAccount? user = _currentUser;
+          final GoogleSignInClientAuthorization? authorization = _authorization;
           final List<Widget> children;
           if (snapshot.hasError) {
             children = <Widget>[
@@ -170,10 +170,10 @@ class SignInDemoState extends State<SignInDemo> {
                   subtitle: Text(user.email),
                 ),
                 const Text('Signed in successfully.'),
-                if (_authorization != null) ...<Widget>[
+                if (authorization != null) ...<Widget>[
                   Text(_contactText),
                   ElevatedButton(
-                    onPressed: _handleGetContact,
+                    onPressed: () => _handleGetContact(authorization),
                     child: const Text('REFRESH'),
                   ),
                 ] else ...<Widget>[

packages/extension_google_sign_in_as_googleapis_auth/lib/extension_google_sign_in_as_googleapis_auth.dart

@@ -15,7 +15,7 @@ extension GoogleApisGoogleSignInAuth on GoogleSignInClientAuthorization {
   /// The [scopes] passed here should be the same as the scopes used to request
   /// the authorization. Passing scopes here that have not been authorized will
   /// likely result in API errors when using the client.
-  gapis.AuthClient? authClient({
+  gapis.AuthClient authClient({
     required List<String> scopes,
   }) {
     final gapis.AccessCredentials credentials = gapis.AccessCredentials(

packages/extension_google_sign_in_as_googleapis_auth/test/extension_google_sign_in_as_googleapis_auth_test.dart

@@ -23,7 +23,7 @@ void main() {
         FakeGoogleSignInClientAuthorization();
     final gapis.AuthClient client = signInAuth.authClient(
       scopes: scopes,
-    )!;
+    );
     expect(client.credentials.accessToken.data, equals(SOME_FAKE_ACCESS_TOKEN));
     expect(client.credentials.scopes, equals(scopes));
   });