Describe the bug
I'm trying to push part of the request json payload into the response body. Unfortunately, it doesn't seem to be working. I have tested multiple scenarios and part or the full object is pushed into the response as a String (instead of the json format).

To Reproduce
Steps to reproduce the behavior:

1. Send this payload
   { "supportingService": [ { "isBundle": false, "serviceDate": "2023-09-22T12:02:50.050Z", "supportingResource": [], "@type": "Service", "hasStarted": true, "serviceSpecification": { "@referredType": "ServiceSpecification", "@type": "serviceSpecification", "name": "Points to ETH OVC RFS", "id": "RFS002" }, "description": "ETH OVC Service", "supportingService": [ { "isBundle": false, "serviceDate": "2023-09-22T12:02:50.050Z", "supportingResource": [], "@type": "Service", "hasStarted": true, "serviceSpecification": { "@referredType": "ServiceSpecification", "@type": "serviceSpecification", "name": "Points to ETH ENNI RFS", "id": "RFS003" }, "description": "ETH ENNI RFS", "supportingService": [], "relatedParty": [], "isServiceEnabled": true, "feature": [], "id": "1691445769362", "state": "active", "category": "SATCOM Services", "startDate": "2023-09-22T12:02:50.050Z", "isStateful": true, "serviceCharacteristic": [ { "valueType": "string", "name": "mef-service-type", "id": "0001", "value": "POINT_TO_POINT_CONNECTIVITY" }, { "valueType": "string", "name": "mef-service-level", "id": "0002", "value": "GUARANTEED" }, { "valueType": "long", "name": "rfSvcTemplateId", "id": "0003", "value": 1691445769351 }, { "valueType": "long", "name": "switchId", "id": "0004", "value": 1691524921187 }, { "valueType": "long", "name": "modemId", "id": "0005", "value": 1691445769361 }, { "valueType": "long", "name": "servicePointId", "id": "0006", "value": 1691166338810 }, { "valueType": "long", "name": "CIR", "id": "0007", "value": 4500000 }, { "valueType": "long", "name": "CBS", "id": "0008", "value": 2500000 }, { "valueType": "long", "name": "vlanNumber", "id": "0009", "value": 2102 }, { "valueType": "long", "name": "satId", "id": "00010", "value": 1692975830389 } ] } ], "relatedParty": [], "isServiceEnabled": true, "feature": [], "id": "1691524921186", "state": "active", "category": "SATCOM Services", "startDate": "2023-09-22T12:02:50.050Z", "isStateful": true, "serviceCharacteristic": [ { "valueType": "string", "name": "gatewayName", "id": "0001", "value": "TMF-GW" } ] } ] }

2. Configure the Body as:
   {"serviceSpecification": ${BODY_JSON_PATH(expression="$.supportingService[0].serviceSpecification")} }

3. Configure the response header: Content-Type: application/json

4. Use postman to trigger the request

5. See the error on the response

{ "serviceSpecification": {@referredType=ServiceSpecification, @type=serviceSpecification, name=Points to ETH OVC RFS, id=RFS002 } }

Expected behavior
My expectation is that the body contains a correct json format.

Screenshots

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• Java: openjdk 21-ea 2023-09-19