If you look at the instructions here
https://docs.jiwa.com.au/display/J7UG/W ... bscription and ignore the plugin which provides a screen inside Jiwa to make if possible to do it in Jiwa, you don't need a plugin, you simply need to register a subscriber and then the appropriate subscriptions for the events you wish to receive.
As stated registering a subscriber and subscriptions through the api will make the necessary entries in the tables inside the Jiwa database so that the webhooks system will send the data for the events to the appropriate endpoints when the events happen in Jiwa.
In other words it's the data in these tables that will make the whole thing work, not code, the code exists out of the box with Jiwa to make the whole thing work provided there is data in the tables to act as as the instructions on what to do and when.
The list of possible events you can create a subscription to are covered here
https://docs.jiwa.com.au/display/J7UG/W ... hookEvents