UBER-914: map to mixin after findAll (#3745)

Signed-off-by: Vyacheslav Tumanov <me@slavatumanov.me>

server-plugins/notification/src/index.ts

@@ -76,7 +76,7 @@ export async function getEmployee (employee: Ref<Employee>, control: TriggerCont
       { limit: 1 }
     )
   )[0]
-  return account
+  return account !== undefined ? control.hierarchy.as(account, contact.mixin.Employee) : undefined
 }
 
 /**