Show a warning when a module uses a v1 only plugin (flutter#44499)

Author: xster

packages/flutter_tools/lib/src/plugins.dart

@@ -402,6 +402,16 @@ Future<void> _writeAndroidPluginRegistrant(FlutterProject project, List<Plugin>
       for (Map<String, dynamic> plugin in androidPlugins) {
         if (plugin['supportsEmbeddingV1'] && !plugin['supportsEmbeddingV2']) {
           templateContext['needsShim'] = true;
+          if (project.isModule) {
+            printStatus(
+              'The plugin `${plugin['name']}` is built using an older version '
+              "of the Android plugin API which assumes that it's running in a "
+              'full-Flutter environment. It may have undefined behaviors when '
+              'Flutter is integrated into an existing app as a module.\n'
+              'The plugin can be updated to the v2 Android Plugin APIs by '
+              'following https://flutter.dev/go/android-plugin-migration.'
+            );
+          }
           break;
         }
       }

packages/flutter_tools/lib/src/project.dart

@@ -645,6 +645,11 @@ class AndroidProject {
   }
 
   AndroidEmbeddingVersion getEmbeddingVersion() {
+    if (isModule) {
+      // A module type's Android project is used in add-to-app scenarios and
+      // only supports the V2 embedding.
+      return AndroidEmbeddingVersion.v2;
+    }
     if (appManifestFile == null || !appManifestFile.existsSync()) {
       return AndroidEmbeddingVersion.v1;
     }