如何将AdListener设置为null

我有一个横幅广告和它的回调,但当我完成活动时,LeakCanary显示内存泄漏:

com.android.gms,ads.nonagon.ad.webview

泄漏:是(View.mContext引用了已销毁的活动)

我在onDestroy中销毁了adView,但泄漏仍然发生。我认为问题可能来自 binding.adView.adListener = object : AdListener() { } 。如何在中将adListener设置为null onDestroy ?

override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

    val adRequest = AdRequest.Builder().build()
    binding.adView.loadAd(adRequest)

    binding.adView.adListener = object : AdListener() {
         // callbacks ...
    }
}

override fun onDestroy() {
    super.onDestroy()

    binding.adView.destroy()
}

XML文件:

<com.google.android.gms.ads.AdView
    xmlns:ads="http://schemas.android.com/apk/res-auto"
    android:id="@+id/adView"
    ads:adSize="BANNER"
    ads:adUnitId="ca-app-pub-3940256099942544/6300978111">
    // ...
</com.google.android.gms.ads.AdView>