add deprecation message

Author: cynthiajoan

packages/firebase_ai/firebase_ai/lib/src/firebase_ai.dart

@@ -62,7 +62,11 @@ class FirebaseAI extends FirebasePluginPlatform {
   /// If pass in [appCheck], request session will get protected from abusing.
   static FirebaseAI vertexAI({
     FirebaseApp? app,
+    @Deprecated(
+        'Passing an explicit instance is deprecated, internal handling is now automatic.')
     FirebaseAppCheck? appCheck,
+    @Deprecated(
+        'Passing an explicit instance is deprecated, internal handling is now automatic.')
     FirebaseAuth? auth,
     String? location,
     bool? useLimitedUseAppCheckTokens,
@@ -97,7 +101,11 @@ class FirebaseAI extends FirebasePluginPlatform {
   /// If pass in [appCheck], request session will get protected from abusing.
   static FirebaseAI googleAI({
     FirebaseApp? app,
+    @Deprecated(
+        'Passing an explicit instance is deprecated, internal handling is now automatic.')
     FirebaseAppCheck? appCheck,
+    @Deprecated(
+        'Passing an explicit instance is deprecated, internal handling is now automatic.')
     FirebaseAuth? auth,
     bool? useLimitedUseAppCheckTokens,
   }) {

packages/firebase_app_check/firebase_app_check/lib/src/firebase_app_check.dart

@@ -5,7 +5,8 @@
 
 part of '../firebase_app_check.dart';
 
-class FirebaseAppCheck extends FirebasePluginPlatform implements FirebaseService {
+class FirebaseAppCheck extends FirebasePluginPlatform
+    implements FirebaseService {
   static Map<String, FirebaseAppCheck> _firebaseAppCheckInstances = {};
 
   FirebaseAppCheck._({required this.app})

packages/firebase_core/firebase_core/test/firebase_core_test.dart

@@ -67,10 +67,10 @@ void main() {
 
     test('.registerService() and .getService()', () {
       FirebaseApp app = Firebase.app(testAppName);
-      
+
       final testService = TestService();
       app.registerService<TestService>(testService);
-      
+
       expect(app.getService<TestService>(), testService);
     });
   });