title: Logstash aggregate filter: start event but no stop event
body: <p>I have log messages which I want to aggregate looking somthing like this:</p>
  
  <p>I left out everything non essential to the question (such as a common ID in all messages)</p>
  
  <blockquote>
    <p>Start 1</p>
    
    <p>2</p>
    
    <p>3</p>
    
    <p>Start a</p>
    
    <p>b </p>
    
    <p>c</p>
  </blockquote>
  
  <p>I want to aggregate all messages between to starts --> Start 1 2 3 and Start a b c</p>
  
  <p>The <a href="https://www.elastic.co/guide/en/logstash/current/plugins-filters-aggregate.html#plugins-filters-aggregate" rel="nofollow noreferrer">aggregate filter documentation</a> states that when there is no end event, timeouts should be used. My problem is that a timeout is not enough because Start 1 and Start a might happen almost simultaniously and will therefore be aggregated to --> start123abc.</p>
  
  <p>Is there a way to "close" a previous aggregation when a new message begins with start?</p>