<aggregate>
   <correlateOn expression="xpath | json-path"/>?
   <completeCondition [timeout="time-in-seconds"]>
     <messageCount min="int-min" max="int-max"/>?
   </completeCondition>?
   <onComplete expression="xpath | json-path" [sequence="sequence-ref"]>
     (mediator +)?
   </onComplete>
</aggregate>