Canonical GeneratedPluginLoader usage

MainActivity.java

// This example assumes that the developer is using the new Android embedding
// API, as well as plugins that have opted-in to the proposed dart-side
// plugin initialization.
public class MainActivity extends FlutterActivity {
  @Override
  protected void onFlutterEngineCreated(@NonNull FlutterEngine engine) {
    engine.setPluginLoader(new GeneratedPluginLoader());
  }
}