错误：找不到符号FirebaseAdMobPlugin.registerNativeAdFactory（flutterEngine，“ moviesTorrentAdFactory”，NativeAdFactoryExample（））;

Question

我正在使用flutter，并且在此doc

之后，我尝试使用原生广告

所有广告都可以正常运行，但原生广告无法正常运行，并且无法构建显示此错误的应用程序

错误：找不到符号FirebaseAdMobPlugin.registerNativeAdFactory（flutterEngine，“ moviesTorrentAdFactory”，NativeAdFactoryExample（））;

这是MyActivity.java文件：

package tech.devm.movies_torrent;

import io.flutter.embedding.android.FlutterActivity;
import io.flutter.embedding.engine.FlutterEngine;
import io.flutter.plugins.firebaseadmob.FirebaseAdMobPlugin;

import com.google.android.gms.ads.formats.UnifiedNativeAd;
import com.google.android.gms.ads.formats.UnifiedNativeAdView;
import io.flutter.plugins.firebaseadmob.FirebaseAdMobPlugin.NativeAdFactory;
import java.util.Map;

public class MainActivity extends FlutterActivity {
  @Override
  public void configureFlutterEngine(FlutterEngine flutterEngine) {
    flutterEngine.getPlugins().add(new FirebaseAdMobPlugin());

    FirebaseAdMobPlugin.registerNativeAdFactory(flutterEngine, "moviesTorrentAdFactory", NativeAdFactoryExample());
  }

  @Override
  public void cleanUpFlutterEngine(FlutterEngine flutterEngine) {
    FirebaseAdMobPlugin.unregisterNativeAdFactory(flutterEngine, "moviesTorrentAdFactory");
  }
}




class NativeAdFactoryExample implements NativeAdFactory {
  @Override
  public UnifiedNativeAdView createNativeAd(
      UnifiedNativeAd nativeAd, Map<String, Object> customOptions) {
    // Create UnifiedNativeAdView
  }
}

是否应该对Manifest.xml文件进行任何更改？还是我错过了什么？ 我已经使用（flutter clean）多次清除了构建，但是没有任何效果 任何帮助将不胜感激