Your listener id (must be unique)
Your listener function
// log a message in the console each time an extension has been unregistered
JMap.Event.Extension.on.unregistration(
"custom-core-extension-unregistration",
params => console.log(`Extension id="${params.extensionId}" has been unregistered`)
)
JMap.Event.Extension.on.unregistration
This event is triggered when an extension is unregistered.