How to get extra string value when using custom UnityPlayerActivity

Hi. I'm trying to implement some automated test for Unity Android app.

Here is my C# code for getting extra value from intent:

Code (CSharp):

1. var playerClass = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
2. var activity = playerClass.GetStatic<AndroidJavaObject>("currentActivity");
3. var intent = activity.Call<AndroidJavaObject>("getIntent");
4. var extras = intent.Call<AndroidJavaObject>("getExtras");
5. var value = extras.Call<string>("getString", name);

Then here is app execution command for ADB:

adb shell am start -n my.package/com.unity3d.player.UnityPlayerActivity -e mykey myvalue

Above code works perfectly, and I can read extra string "mykey" from Unity C# code.

But when I extended UnityPlayerActivity to custom activity (https://docs.unity3d.com/Manual/AndroidUnityPlayerActivity.html), it does not work anymore.

I changed adb command for my custom activity like this:

adb shell am start -n my.package/my.app.CustomUnityPlayerActivity -e mykey myvalue

App is successfully executed, but its extra value always return null.

Any ideas?

Thanks.