Question About Notification Listener Extension - for specific Application

I saw the Notification Listener extension.
I would like to know if there is the possibility of being able to record the notifications of a single and specific Application.
I am a beginner and I honestly don't know how.
Some advice?

currently there is no possibility to filter for a specific app, but I could look into it how this could be added...

PS: in case someone else likes to give it a try... the extensions is open source and the source code is available here

Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by icon24 Taifun.