Setting up Transaction Event Handlers


I am looking for some help on setting up Transaction Event Handlers.

I see that custom event handlers are available here:

My question is where to put these files in the neo4j file structure? Is there any documentation I can read or tutorials on how to set these up?

Thanks in advance,

I have created a repo with an example :

I wrote a very similar extension factory class - it works fine in a test with neo4j-harness. Then I copied the jar file into the plugins directory of the database in a Desktop installation, and restarted it, but the event listener doesn't work. Am I missing a step?