Merge message with aggregate filter

Hi,

maybe I am on the completely wrong track but I would expect 1 document: (when event cancel is active I get nothing)

  {
      "Type" => "REQ_OUT",
  "@version" => "1",
      "host" => "LGS02",
"ExchangeId" => "260e06a3-9cb5-4154-bf97-637e929fa4c2",
"@timestamp" => 2021-04-14T06:46:29.221Z,
      "path" => "/tmp/test.txt"
	  "REQ_OUT" => {
	    "timestamp" => "2021-04-02T05:50:45.534Z",
		"severity" => "INFO",
		...
	  
	  }
	  "RESP_IN" => {
	    "timestamp" => "2021-04-02T05:50:44.251Z",
		"severity" => "INFO",
		ResponseCode" => "200",
		...
	  }
  "@version" => "1",
      "host" => "LGS02",
"ExchangeId" => "260e06a3-9cb5-4154-bf97-637e929fa4c2",
"@timestamp" => 2021-04-14T06:46:29.247Z,
      "path" => "/tmp/test.txt"

}