private long sessionTimeoutMillis() {
        return params.getSessionTimeoutMs();
    }
A session is considered completed iff
<p>
<em>All</em> the following holds true:
<ul>
  <li>We have no outbound requests pending towards the content cluster,
      i.e. we're waiting for replies.</li>
  <li>We have no inbound requests from the content nodes that we have
      yet to acknowledge, i.e. we are async processing a put/remove from
      the content cluster.</li>
</ul>
</p><p>
<em>And</em> if <em>one or more</em> of the following holds true:
<ul>
  <li>All buckets have been visited (i.e. no active or pending visitors).</li>
  <li>Visiting has failed fatally (or has been aborted).</li>
  <li>We have received sufficient number of documents (set via visitor
      parameters) from the buckets already visited <em>and</em> there
      are no active visitors remaining.</li>
</ul>
</p>
@return true if visiting has completed, false otherwise
documentapi/src/main/java/com/yahoo/documentapi/messagebus/MessageBusVisitorSession.java