Hi,
We have updated the sample application that shows appIcon as a default when Push Notification receives. You can start with the updated sample or you can download library jar file from Drop-Box and can replace it in Assets\Plugins\Android folder.
https://www.dropbox.com/s/tjrbryn8lf0b96a/app42pushservice.jar?dl=0
Let me know if it helps.
Thanks & Regards
Vishnu Garg