How to create custom event type with UA-.NetStandardLibrary?|OPC UA Implementation: Stacks, Tools, and Samples|Forum|OPC Foundation

I am trying to create a custom event by inheriting BaseEventState in UA.NetStandard. However for me it is unclear how to create a custom type that can be shown in the Types/EventTypes/BaseEventType node.

I have also failed trying to add properties to the BaseEvent and thereby extending this object using InstanceStateSnapshot and SetChildValue. A custom type for this shown in the Types/EventTypes/BaseEventType node for this approach would be good as well.

Please, can I have some pointers?