Since an Epic by design is not associated with a Sprint, it can not be included in a JQL query with a function like this. The goal is to create a filter that could be fed to a dashboard that includes only Epics that have linked issues (other parents) in open sprints...and be able to include them with the linked issues...better yet, extract just the Epics. Is there a solution for a Cloud user?
sprint in openSprints()