admobadapter/src/main/java/com/clockbyte/admobadapter/expressads/AdmobFetcherExpress.java
protected synchronized void setupAd(final NativeExpressAdView adView) {
        if(mFetchFailCount > MAX_FETCH_ATTEMPT)
            return;

        if(!mPrefetchedAds.contains(adView))
            mPrefetchedAds.add(adView);
        adView.setAdListener(new AdListener() {
            @Override
            public void onAdFailedToLoad(int errorCode) {
                super.onAdFailedToLoad(errorCode);
                // Handle the failure by logging, altering the UI, etc.
                onFailedToLoad(adView, errorCode);
            }
            @Override
            public void onAdLoaded() {
                super.onAdLoaded();
                onFetched(adView);
            }
        });
    }
protected synchronized void setupAd(final NativeExpressAdView adView) {
        if(mFetchFailCount > MAX_FETCH_ATTEMPT)
            return;

        if(!mPrefetchedAds.contains(adView))
            mPrefetchedAds.add(adView);
        adView.setAdListener(new AdListener() {
            @Override
            public void onAdFailedToLoad(int errorCode) {
                super.onAdFailedToLoad(errorCode);
                // Handle the failure by logging, altering the UI, etc.
                onFailedToLoad(adView, errorCode);
            }
            @Override
            public void onAdLoaded() {
                super.onAdLoaded();
                onFetched(adView);
            }
        });
    }
Subscribing to the native ads events
@param adView