Create ticket via work items API

In Create Service Desk tickets from the UI and API (#433376 - closed) we added the functionality to create Service Desk issues via the API and UI using a quick action that converts a regular issue into a Service Desk issue.

When we migrate Service Desk issues to the work item framework we need to ensure you can create tickets via the work item framework.

A ticket needs an additional parameter the external_author (email address) and maybe a list of additional external participants.