This type afaik is used for internal mapping - to create a pin-like object from platform event, so that might need to keep. What we need to remove though is that part from blobdb where we assign icons based on the type (BlobDB::insertNotification) - maybe move it to notification - so that should be able to cast itself to the TimelineItem.

Ideally platform integration layer should come up with proper json document and just feed it to the timeline engine. In that case we can remove of course all these proxy objects like notifications and calendar-events working purely with the timeine api to manage all kind of notifications. Or with raw TimelineItem - to avoid double conversion (for one-offs).