The stated purpose of this is for "sending unsolicited notifications to the appropriate actors when triggered by an event or request". The example use case is for admission and discharge. On the html web page listed (or here http://hl7.org/fhir/us/davinci-alerts/2020FEB/usecases.html) Figure 5 shows the encounter diagnosis. It isn't required but including it seems very odd. Typically an encounter diagnosis is not available until well after discharge. If the purpose is to give an immediate notification when a patient is discharged, then why would you even list this element. It puts pressure on implementers to try to provide it or at least to look into it. Why not just leave it off and allow systems to query for it later?