Move the plugin registrant to io.flutter.plugins and add the @Keep annotation (#44011)

dev/integration_tests/android_embedding_v2_smoke_test/android/app/src/main/kotlin/com/example/android_embedding_v2_smoke_test/MainActivity.kt

 package com.example.android_embedding_v2_smoke_test
 
 import androidx.annotation.NonNull;
-import dev.flutter.plugins.GeneratedPluginRegistrant
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugins.GeneratedPluginRegistrant
 
 class MainActivity: FlutterActivity() {
     override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {

dev/integration_tests/android_host_app_v2_embedding/app/src/main/java/io/flutter/add2app/MainActivity.java

 package io.flutter.add2app;
 
 import androidx.annotation.NonNull;
-import dev.flutter.plugins.GeneratedPluginRegistrant;
 import io.flutter.embedding.android.FlutterActivity;
 import io.flutter.embedding.engine.FlutterEngine;
+import io.flutter.plugins.GeneratedPluginRegistrant;
 
 public class MainActivity extends FlutterActivity {
   @Override

dev/integration_tests/android_module_host_with_custom_build_v2_embedding/app/src/main/java/io/flutter/addtoapp/MainActivity.java

 package io.flutter.add2app;
 
 import androidx.annotation.NonNull;
-import dev.flutter.plugins.GeneratedPluginRegistrant;
 import io.flutter.embedding.android.FlutterActivity;
 import io.flutter.embedding.engine.FlutterEngine;
+import io.flutter.plugins.GeneratedPluginRegistrant;
 
 public class MainActivity extends FlutterActivity {
   @Override

dev/integration_tests/module_host_with_custom_build_v2_embedding/app/src/main/java/io/flutter/addtoapp/MainActivity.java

 package io.flutter.add2app;
 
 import androidx.annotation.NonNull;
-import dev.flutter.plugins.GeneratedPluginRegistrant;
 import io.flutter.embedding.android.FlutterActivity;
 import io.flutter.embedding.engine.FlutterEngine;
+import io.flutter.plugins.GeneratedPluginRegistrant;
 
 public class MainActivity extends FlutterActivity {
   @Override

packages/flutter_tools/lib/src/plugins.dart

@@ -311,12 +311,14 @@ public final class GeneratedPluginRegistrant {
 }
 ''';
 
-const String _androidPluginRegistryTemplateNewEmbedding = '''package dev.flutter.plugins;
+const String _androidPluginRegistryTemplateNewEmbedding = '''package io.flutter.plugins;
 
 {{#androidX}}
+import androidx.annotation.Keep;
 import androidx.annotation.NonNull;
 {{/androidX}}
 {{^androidX}}
+import android.support.annotation.Keep;
 import android.support.annotation.NonNull;
 {{/androidX}}
 import io.flutter.embedding.engine.FlutterEngine;
@@ -329,6 +331,7 @@ import io.flutter.embedding.engine.plugins.shim.ShimPluginRegistry;
  * This file is generated by the Flutter tool based on the
  * plugins that support the Android platform.
  */
+@Keep
 public final class GeneratedPluginRegistrant {
   public static void registerWith(@NonNull FlutterEngine flutterEngine) {
 {{#needsShim}}
@@ -399,10 +402,14 @@ Future<void> _writeAndroidPluginRegistrant(FlutterProject project, List<Plugin>
     'main',
     'java',
   );
-
-  String registryPath;
+  final String registryPath = fs.path.join(
+    javaSourcePath,
+    'io',
+    'flutter',
+    'plugins',
+    'GeneratedPluginRegistrant.java',
+  );
   String templateContent;
-
   final String appEmbeddingVersion = _getAndroidEmbeddingVersion(project);
   switch (appEmbeddingVersion) {
     case '2':
@@ -415,23 +422,9 @@ Future<void> _writeAndroidPluginRegistrant(FlutterProject project, List<Plugin>
           break;
         }
       }
-      registryPath = fs.path.join(
-        javaSourcePath,
-        'dev',
-        'flutter',
-        'plugins',
-        'GeneratedPluginRegistrant.java',
-      );
       templateContent = _androidPluginRegistryTemplateNewEmbedding;
     break;
     case '1':
-      registryPath = fs.path.join(
-        javaSourcePath,
-        'io',
-        'flutter',
-        'plugins',
-        'GeneratedPluginRegistrant.java',
-      );
       templateContent = _androidPluginRegistryTemplateOldEmbedding;
     break;
     default:

packages/flutter_tools/templates/app/android-java.tmpl/app/src/main/java/androidIdentifier/MainActivity.java.tmpl

@@ -7,9 +7,9 @@ import androidx.annotation.NonNull;
 {{^androidX}}
 import android.support.annotation.NonNull;
 {{/androidX}}
-import dev.flutter.plugins.GeneratedPluginRegistrant;
 import io.flutter.embedding.android.FlutterActivity;
 import io.flutter.embedding.engine.FlutterEngine;
+import io.flutter.plugins.GeneratedPluginRegistrant;
 
 public class MainActivity extends FlutterActivity {
   @Override

packages/flutter_tools/templates/app/android-kotlin.tmpl/app/src/main/kotlin/androidIdentifier/MainActivity.kt.tmpl

@@ -7,9 +7,9 @@ import androidx.annotation.NonNull;
 {{^androidX}}
 import android.support.annotation.NonNull;
 {{/androidX}}
-import dev.flutter.plugins.GeneratedPluginRegistrant
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugins.GeneratedPluginRegistrant
 
 class MainActivity: FlutterActivity() {
     override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {

packages/flutter_tools/templates/module/android/host_app_common/app.tmpl/src/main/java/androidIdentifier/host/MainActivity.java.tmpl

@@ -8,9 +8,9 @@ import androidx.annotation.NonNull;
 {{^androidX}}
 import android.support.annotation.NonNull;
 {{/androidX}}
-import dev.flutter.plugins.GeneratedPluginRegistrant;
 import io.flutter.embedding.android.FlutterActivity;
 import io.flutter.embedding.engine.FlutterEngine;
+import io.flutter.plugins.GeneratedPluginRegistrant;
 
 public class MainActivity extends FlutterActivity {
   @Override

packages/flutter_tools/test/general.shard/plugins_test.dart

@@ -190,11 +190,11 @@ void main() {
         await injectPlugins(flutterProject);
 
         final File registrant = flutterProject.directory
-          .childDirectory(fs.path.join('android', 'app', 'src', 'main', 'java', 'dev', 'flutter', 'plugins'))
+          .childDirectory(fs.path.join('android', 'app', 'src', 'main', 'java', 'io', 'flutter', 'plugins'))
           .childFile('GeneratedPluginRegistrant.java');
 
         expect(registrant.existsSync(), isTrue);
-        expect(registrant.readAsStringSync(), contains('package dev.flutter.plugins'));
+        expect(registrant.readAsStringSync(), contains('package io.flutter.plugins'));
         expect(registrant.readAsStringSync(), contains('class GeneratedPluginRegistrant'));
       }, overrides: <Type, Generator>{
         FileSystem: () => fs,
@@ -282,7 +282,7 @@ plugin3:${pluginUsingOldEmbeddingDir.childDirectory('lib').uri.toString()}
         await injectPlugins(flutterProject);
 
         final File registrant = flutterProject.directory
-          .childDirectory(fs.path.join('android', 'app', 'src', 'main', 'java', 'dev', 'flutter', 'plugins'))
+          .childDirectory(fs.path.join('android', 'app', 'src', 'main', 'java', 'io', 'flutter', 'plugins'))
           .childFile('GeneratedPluginRegistrant.java');
 
         expect(registrant.readAsStringSync(),
@@ -362,11 +362,11 @@ plugin3:${pluginUsingOldEmbeddingDir.childDirectory('lib').uri.toString()}
         await injectPlugins(flutterProject);
 
         final File registrant = flutterProject.directory
-          .childDirectory(fs.path.join('android', 'app', 'src', 'main', 'java', 'dev', 'flutter', 'plugins'))
+          .childDirectory(fs.path.join('android', 'app', 'src', 'main', 'java', 'io', 'flutter', 'plugins'))
           .childFile('GeneratedPluginRegistrant.java');
 
         expect(registrant.existsSync(), isTrue);
-        expect(registrant.readAsStringSync(), contains('package dev.flutter.plugins'));
+        expect(registrant.readAsStringSync(), contains('package io.flutter.plugins'));
         expect(registrant.readAsStringSync(), contains('class GeneratedPluginRegistrant'));
       }, overrides: <Type, Generator>{
         FileSystem: () => fs,