How to compare fields between 2 JSON objects and create a response JSON in Jolt

[Madhavi56]

Request:

{
  "request1": {
    "firm": {
      "item": [
        {
          "Du": "1234",
          "Gu": "123",
          "DuNm": "QWERTy",
          "Don":{
            "donType":"Modern",
            "donValue":"0002"
          }

        }
      ]
    }
  },
  "request2": {
    "firm": {
      "item": [
        {
          "Du": "999999999",
          "Gu": "999999999",
          "GuNm": "Sample",
          "Mad":"Fluffy",
          "isInt":true,
          "Dusky":{
            "duskyType":"Modern",
            "duskyValue":"0002"
          }
        }
      ]
    }
  }
}

Desired Response:

{
  "original": {
    "Du": "999999999",
    "Gu": "999999999",
    "DuNm": "",
      "Don":{}
  }
}

Jolt:

Jolt I am trying so far

[
  {
    "operation": "shift",
    "spec": {
      "request1": {
        "firm": {
          "item": {
            "*": {
              "*": {
                "@5,request2.firm.item": {
                  "*": {
                    "@(&1)": "original.&2"
                  }
                }
              }
            }
          }
        }
      }
    }
  }
]

Output I am getting:

{
  "original" : {
    "Du" : "999999999",
    "Gu" : "999999999"
  }
}

I want to check if the field in request1 is there or not in request2, if it is then add it in the response with the value present in request2. if the String field is not there in request2 then the its value should go as "" in output.if the Object field is not there in request2 then the its value should go as {} in output. The request1 and request2 can have multiple different fields at each time.