fix(ui_auth): deprecate email enumeration protection affected APIs

packages/firebase_ui_auth/lib/firebase_ui_auth.dart

@@ -29,6 +29,7 @@ export 'src/auth_state.dart'
         SigningIn,
         UserCreated,
         AuthFailed,
+        // ignore: deprecated_member_use_from_same_package
         DifferentSignInMethodsFound,
         MFARequired;
 export 'src/email_verification.dart';

packages/firebase_ui_auth/lib/src/auth_flow.dart

@@ -128,6 +128,11 @@ class AuthFlow<T extends AuthProvider> extends ValueNotifier<AuthState>
     value = CredentialLinked(credential, auth.currentUser!);
   }
 
+  @override
+  @Deprecated(
+    'Email enumeration protection is on by default.'
+    'Read more here https://cloud.google.com/identity-platform/docs/admin/email-enumeration-protection',
+  )
   @override
   void onDifferentProvidersFound(
     String email,

packages/firebase_ui_auth/lib/src/auth_state.dart

@@ -160,6 +160,10 @@ class UserCreated extends AuthState {
 ///
 /// See [AuthState] docs for usage examples.
 /// {@endtemplate}
+@Deprecated(
+  'Email enumeration protection is on by default.'
+  'Read more here https://cloud.google.com/identity-platform/docs/admin/email-enumeration-protection',
+)
 class DifferentSignInMethodsFound extends AuthState {
   /// An email that has different auth providers associated with.
   final String email;

packages/firebase_ui_auth/lib/src/navigation/authentication.dart

@@ -45,6 +45,10 @@ Future<bool> showReauthenticateDialog({
 }
 
 /// Shows [DifferentMethodSignInDialog].
+@Deprecated(
+  'Email enumeration protection is on by default.'
+  'Read more here https://cloud.google.com/identity-platform/docs/admin/email-enumeration-protection',
+)
 Future<void> showDifferentMethodSignInDialog({
   required BuildContext context,
 

packages/firebase_ui_auth/lib/src/providers/auth_provider.dart

@@ -6,11 +6,8 @@ import 'package:firebase_auth/firebase_auth.dart' as fba;
 import 'package:flutter/material.dart';
 import 'package:firebase_ui_auth/firebase_ui_auth.dart';
 
-/// Default error handler that fetches available providers if
-/// `account-exists-with-different-credential` was thrown.
-///
-/// After succesful execution, auth flow should have
-/// [DifferentSignInMethodsFound] state.
+/// Default error handler that starts MFA flow
+/// if [FirebaseAuthMultiFactorException] is thrown.
 void defaultOnAuthError(AuthProvider provider, Object error) {
   if (error is! fba.FirebaseAuthException) {
     throw error;

packages/firebase_ui_auth/lib/src/screens/sign_in_screen.dart

@@ -126,8 +126,10 @@ class SignInScreen extends MultiProviderScreen {
 
   Future<void> _signInWithDifferentProvider(
     BuildContext context,
+    // ignore: deprecated_member_use_from_same_package
     DifferentSignInMethodsFound state,
   ) async {
+    // ignore: deprecated_member_use_from_same_package
     await showDifferentMethodSignInDialog(
       availableProviders: state.methods,
       providers: providers,
@@ -145,6 +147,7 @@ class SignInScreen extends MultiProviderScreen {
   Widget build(BuildContext context) {
     final handlesDifferentSignInMethod = this
         .actions
+        // ignore: deprecated_member_use_from_same_package
         .whereType<AuthStateChangeAction<DifferentSignInMethodsFound>>()
         .isNotEmpty;
 

packages/firebase_ui_auth/lib/src/views/different_method_sign_in_view.dart

@@ -10,6 +10,10 @@ import 'package:firebase_ui_auth/firebase_ui_auth.dart';
 /// A view that renders a list of providers that were previously used by the
 /// user to authenticate.
 /// {@endtemplate}
+@Deprecated(
+  'Email enumeration protection is on by default.'
+  'Read more here https://cloud.google.com/identity-platform/docs/admin/email-enumeration-protection',
+)
 class DifferentMethodSignInView extends StatelessWidget {
   /// {@macro ui.auth.auth_controller.auth}
   final fba.FirebaseAuth? auth;

packages/firebase_ui_auth/lib/src/widgets/different_method_sign_in_dialog.dart

@@ -14,6 +14,10 @@ import '../widgets/internal/title.dart';
 /// A dialog that is shown when the user tries to sign in with a provider that
 /// wasn't previously used, but there are other providers for a given email.
 /// {@endtemplate}
+@Deprecated(
+  'Email enumeration protection is on by default.'
+  'Read more here https://cloud.google.com/identity-platform/docs/admin/email-enumeration-protection',
+)
 class DifferentMethodSignInDialog extends StatelessWidget {
   /// {@macro ui.auth.auth_controller.auth}
   final fba.FirebaseAuth? auth;

packages/firebase_ui_auth/test/widgets/dialogs_test.dart

@@ -31,23 +31,4 @@ void main() {
       expect(find.text('Cancel'), findsOneWidget);
     });
   });
-
-  group('$DifferentMethodSignInDialog', () {
-    testWidgets('has capitalized Cancel label', (tester) async {
-      await tester.pumpWidget(
-        TestMaterialApp(
-          child: DifferentMethodSignInDialog(
-            auth: auth,
-            availableProviders: const ['email', 'phone'],
-            providers: [
-              EmailAuthProvider(),
-              PhoneAuthProvider(),
-            ],
-          ),
-        ),
-      );
-
-      expect(find.text('Cancel'), findsOneWidget);
-    });
-  });
 }