Ionic 4 : How to change small icon in Onesignal

Ionic Framework
1

How to change small icon image in one signal notifications ?

When I tried to change by using ic_stat_onesignal_default image from below path, it is showing grey box instead of image.
platforms/android/app/src/main/res/diff-size-foldername/ic_stat_onesignal_default.png

Can anyone please help me on this?

2

Did you use Android Asset Studio to create your notification icon ?

http://romannurik.github.io/AndroidAssetStudio/icons-notification.html#source.type=clipart&source.clipart=ac_unit&source.space.trim=1&source.space.pad=0&name=ic_stat_onesignal_default

3

Yes, I have used Android Asset Studio to create notification icon. But it is showing grey box.
When I tried white and transparent image it is working but I need my app icon image in notification small icon. Is there any way to get this?