Forwarding the http input data to http output data

Elastic Stack Logstash
13

Trying something like:

...
		add_field => { 
			"original_message" => "%{[message]}"
		}
...
output {
    file {
        path => "/log_streaming/my_app/log-%{+yyyy-MM-dd_HH.mm.ss.SSS}.log"	
    }
    http {
		http_method=>"post"
		url => "%{[full_url]}"
		content_type => "%{[original_content_type]}"
		message => "%{[original_message]}"
	}
}

correctly, my output file now has original_message as one of the fields:

{
    "message": "{ \"index\" : { \"_index\" : \"journaling_insert\"}}\r\n{\"REMOTEIP\":\"1.111.1.11\",\"CHAINCODE\":\"8971\",\"EVENTID\":\"16\",\"STOREATTRIBUTE3\":\"Passed Value\",\"DATETIME\":\"2025-03-10T15:46:45.215\",\"STOREATTRIBUTE2\":\"StoreDB Value\",\"STOREATTRIBUTE4\":\"StoreDB Value\",\"STOREATTRIBUTE5\":\"StoreDB Value\",\"FLSECURITY\":{\"SID\":\"1111\"},\"FLCUSTOMER\":{\"FIRSTNAME\":\"Francesco\",\"LASTNAME\":\"Esposito\"}}\r\n{ \"index\" : { \"_index\" : \"journaling_insert\"}}\r\n{\"REMOTEIP\":\"1.111.1.11\",\"CHAINCODE\":\"8971\",\"EVENTID\":\"17\",\"DRAWERIDENT\":\"test\",\"DATETIME\":\"2025-03-10T15:46:45.215\",\"STOREATTRIBUTE2\":\"StoreDB Value\",\"STOREATTRIBUTE3\":\"StoreDB Value\",\"STOREATTRIBUTE4\":\"StoreDB Value\",\"STOREATTRIBUTE5\":\"StoreDB Value\",\"FLTRANSACTIONATTRIBUTES\":{\"INVOICENUMBER\":\"1111\"},\"FLCUSTOMER\":{\"FIRSTNAME\":\"Sam\",\"LASTNAME\":\"Stein\"}}\r\n",
    "original_content_type": "application/x-ndjson; charset=utf-8",
    "original_message": "{ \"index\" : { \"_index\" : \"journaling_insert\"}}\r\n{\"REMOTEIP\":\"1.111.1.11\",\"CHAINCODE\":\"8971\",\"EVENTID\":\"16\",\"STOREATTRIBUTE3\":\"Passed Value\",\"DATETIME\":\"2025-03-10T15:46:45.215\",\"STOREATTRIBUTE2\":\"StoreDB Value\",\"STOREATTRIBUTE4\":\"StoreDB Value\",\"STOREATTRIBUTE5\":\"StoreDB Value\",\"FLSECURITY\":{\"SID\":\"1111\"},\"FLCUSTOMER\":{\"FIRSTNAME\":\"Francesco\",\"LASTNAME\":\"Esposito\"}}\r\n{ \"index\" : { \"_index\" : \"journaling_insert\"}}\r\n{\"REMOTEIP\":\"1.111.1.11\",\"CHAINCODE\":\"8971\",\"EVENTID\":\"17\",\"DRAWERIDENT\":\"test\",\"DATETIME\":\"2025-03-10T15:46:45.215\",\"STOREATTRIBUTE2\":\"StoreDB Value\",\"STOREATTRIBUTE3\":\"StoreDB Value\",\"STOREATTRIBUTE4\":\"StoreDB Value\",\"STOREATTRIBUTE5\":\"StoreDB Value\",\"FLTRANSACTIONATTRIBUTES\":{\"INVOICENUMBER\":\"1111\"},\"FLCUSTOMER\":{\"FIRSTNAME\":\"Sam\",\"LASTNAME\":\"Stein\"}}\r\n",
    "headers": {
        "http_accept": "*/*",
        "http_host": "localhost:5043",
        "http_user_agent": "Mozilla/4.0 (compatible; Clever Internet Suite)",
        "content_length": "776",
        "connection": "Keep-Alive",
        "request_method": "POST",
        "cache_control": "no-cache",
        "content_type": "application/x-ndjson; charset=utf-8",
        "request_path": "/_bulk",
        "accept_encoding": "gzip",
        "http_version": "HTTP/1.1"
    },
    "@version": "1",
    "host": "127.0.0.1",
    "original_path": "/_bulk",
    "@timestamp": "2025-03-10T15:46:45.297Z",
    "full_url": "https://esposito.free.beeceptor.com/_bulk"
}

But, I cannot understand why my http message sent to my endpoint simulator is:

{
    "message": "{ \"index\" : { \"_index\" : \"journaling_insert\"}}\r\n{\"REMOTEIP\":\"1.111.1.11\",\"CHAINCODE\":\"8971\",\"EVENTID\":\"16\",\"STOREATTRIBUTE3\":\"Passed Value\",\"DATETIME\":\"2025-03-10T15:46:45.215\",\"STOREATTRIBUTE2\":\"StoreDB Value\",\"STOREATTRIBUTE4\":\"StoreDB Value\",\"STOREATTRIBUTE5\":\"StoreDB Value\",\"FLSECURITY\":{\"SID\":\"1111\"},\"FLCUSTOMER\":{\"FIRSTNAME\":\"Francesco\",\"LASTNAME\":\"Esposito\"}}\r\n{ \"index\" : { \"_index\" : \"journaling_insert\"}}\r\n{\"REMOTEIP\":\"1.111.1.11\",\"CHAINCODE\":\"8971\",\"EVENTID\":\"17\",\"DRAWERIDENT\":\"test\",\"DATETIME\":\"2025-03-10T15:46:45.215\",\"STOREATTRIBUTE2\":\"StoreDB Value\",\"STOREATTRIBUTE3\":\"StoreDB Value\",\"STOREATTRIBUTE4\":\"StoreDB Value\",\"STOREATTRIBUTE5\":\"StoreDB Value\",\"FLTRANSACTIONATTRIBUTES\":{\"INVOICENUMBER\":\"1111\"},\"FLCUSTOMER\":{\"FIRSTNAME\":\"Sam\",\"LASTNAME\":\"Stein\"}}\r\n",
    "original_content_type": "application/x-ndjson; charset=utf-8",
    "original_message": "{ \"index\" : { \"_index\" : \"journaling_insert\"}}\r\n{\"REMOTEIP\":\"1.111.1.11\",\"CHAINCODE\":\"8971\",\"EVENTID\":\"16\",\"STOREATTRIBUTE3\":\"Passed Value\",\"DATETIME\":\"2025-03-10T15:46:45.215\",\"STOREATTRIBUTE2\":\"StoreDB Value\",\"STOREATTRIBUTE4\":\"StoreDB Value\",\"STOREATTRIBUTE5\":\"StoreDB Value\",\"FLSECURITY\":{\"SID\":\"1111\"},\"FLCUSTOMER\":{\"FIRSTNAME\":\"Francesco\",\"LASTNAME\":\"Esposito\"}}\r\n{ \"index\" : { \"_index\" : \"journaling_insert\"}}\r\n{\"REMOTEIP\":\"1.111.1.11\",\"CHAINCODE\":\"8971\",\"EVENTID\":\"17\",\"DRAWERIDENT\":\"test\",\"DATETIME\":\"2025-03-10T15:46:45.215\",\"STOREATTRIBUTE2\":\"StoreDB Value\",\"STOREATTRIBUTE3\":\"StoreDB Value\",\"STOREATTRIBUTE4\":\"StoreDB Value\",\"STOREATTRIBUTE5\":\"StoreDB Value\",\"FLTRANSACTIONATTRIBUTES\":{\"INVOICENUMBER\":\"1111\"},\"FLCUSTOMER\":{\"FIRSTNAME\":\"Sam\",\"LASTNAME\":\"Stein\"}}\r\n",
    "headers": {
        "http_accept": "*/*",
        "http_host": "localhost:5043",
        "http_user_agent": "Mozilla/4.0 (compatible; Clever Internet Suite)",
        "content_length": "776",
        "connection": "Keep-Alive",
        "request_method": "POST",
        "cache_control": "no-cache",
        "content_type": "application/x-ndjson; charset=utf-8",
        "request_path": "/_bulk",
        "accept_encoding": "gzip",
        "http_version": "HTTP/1.1"
    },
    "@version": "1",
    "host": "127.0.0.1",
    "original_path": "/_bulk",
    "@timestamp": "2025-03-10T15:46:45.297Z",
    "full_url": "https://esposito.free.beeceptor.com/_bulk"
}

That's weird! What do you guys think?