Migrate android example app to embedding v2

example/android/app/src/main/AndroidManifest.xml

@@ -6,11 +6,11 @@
          additional functionality it is fine to subclass or reimplement
          FlutterApplication and put your custom class here. -->
     <application
-        android:name="io.flutter.app.FlutterApplication"
+        android:name="${applicationName}"
         android:label="example"
         android:icon="@mipmap/ic_launcher">
         <activity
-            android:name=".MainActivity"
+            android:name="io.flutter.embedding.android.FlutterActivity"
             android:launchMode="singleTop"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"

example/android/app/src/main/java/io/flutter/plugins/GeneratedPluginRegistrant.java

@@ -1,23 +1,19 @@
 package io.flutter.plugins;
 
-import io.flutter.plugin.common.PluginRegistry;
+import androidx.annotation.Keep;
+import androidx.annotation.NonNull;
+import io.flutter.Log;
+
+import io.flutter.embedding.engine.FlutterEngine;
 
 /**
  * Generated file. Do not edit.
+ * 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(PluginRegistry registry) {
-    if (alreadyRegisteredWith(registry)) {
-      return;
-    }
-  }
-
-  private static boolean alreadyRegisteredWith(PluginRegistry registry) {
-    final String key = GeneratedPluginRegistrant.class.getCanonicalName();
-    if (registry.hasPlugin(key)) {
-      return true;
-    }
-    registry.registrarFor(key);
-    return false;
+  private static final String TAG = "GeneratedPluginRegistrant";
+  public static void registerWith(@NonNull FlutterEngine flutterEngine) {
   }
 }