title: Change date on event created by Elapsed or Aggregate filters
body: <p>When using <code>new_event_on_match</code> with elapsed filter a new event is created, with a fresh timestamp. The Aggregate filter adds a new event with a fresh timestamp as well.</p>
  
  <p>I would like to use the timestamp from the original events, which is now available in the field <code>elapsed_timestamp_start</code>. How can I replace <code>@timestamp</code> in the newly created event?</p>
  
  <p>Can I use a <code>Date</code> filter inside an <code>Elapsed</code> filter?</p>