Input

    {
  "request": {
    "PartyStatus": {
      "item": [
        {
          "RleStsVal": {
            "prtyRleStsVal": "0001",
            "prtyRleStsTyp": "Active"
          },
          "PrtyRleStgCd": {
            "PrtyRleStgTp": "0002",
            "PrtyRleStgDesc": "Prospect"
          }
        }
      ]
    },
    "nenId": "OPER1006995",
    "id": "1001",
    "MaskedFlg": true,
    "IsCustFlg": false,
    "PartyAlternateId": {
      "item": [
        {
          "AltIdType": {
            "idTyp": "0002",
            "idTypDesc": "UCM ID"
          },
          "AltIdVal": "B99857DB-5B3C-469a-A976-F504AA74660A"
        },
        {
          "AltIdType": {
            "idTyp": "0001",
            "idTypDesc": "Account Number OU_NUM"
          },
          "AltIdVal": "104267367"
        }
      ]
    }
  },
  "gtResp": {
    "link": [
      {
        "href": "/request",
        "rel": "icon"
      }
    ],
    "PrtnrType": "Reseller",
    "FederalFlg": false,
    "IsCustFlg": false,
    "PartFlg": true,
    "MaskedFlg": false,
    "nenAccTyp": {
      "rowidObject": "2",
      "label": "Lookup nen Account Typr",
      "nenAccTp": "0002",
      "nenAccDesc": "Operational"
    },
    "AccCatTp": {
      "rowidObject": "1",
      "label": "Lookup Account Category",
      "AccCatTP": "0001",
      "accCatDesc": "Billing"
    },
    "nenClnsdNm": "Virtual Machine Technology Pty Ltd",
    "frtSubDivision": false,
    "EndCustName": "5C26-4c61-A73D-6324AEC3951A",
    "prtyReMatchFlag": false,
    "dgtlAccFlg": "N",
    "PartyAlternateId": {
      "link": [],
      "firstRecord": 1,
      "pageSize": 10,
      "ST": "multi",
      "item": [
        {
          "rowidObject": "1801667       ",
          "label": "Party Alternate Id",
          "AltIdVal": "B6C6C095-7924-490a-BFF8-325F43921F3A",
          "AltIdType": {
            "rowidObject": "20006",
            "label": "Lookup Alternate Id Type",
            "idTyp": "0006",
            "idTypDesc": "Ultimate Sales Account"
          }
        },
        {
          "rowidObject": "1801668",
          "label": "Party Alternate Id",
          "AltIdVal": "46C01DCD-64E3-47c5-98B3-E1E0F029EDD9",
          "AltIdType": {
            "rowidObject": "20007",
            "label": "Lookup Alternate Id Type",
            "idTyp": "0007",
            "idTypDesc": "Sales Account UCM ID"
          }
        },
        {
          "rowidObject": "12880628",
          "label": "Party Alternate Id",
          "AltIdVal": "91109",
          "AltIdType": {
            "rowidObject": "20008",
            "label": "Lookup Alternate Id Type",
            "idTyp": "0001",
          "idTypDesc": "Account Number OU_NUM"
          }
        },
        {
          "rowidObject": "12880622",
          "label": "Party Alternate Id",
          "AltIdVal": "5D4F54B8-5C26-4c61-A73D-6324AEC3951A",
          "EffStrtDt": "2022-02-04",
          "AltIdType": {
            "rowidObject": "20002",
            "label": "Lookup Alternate Id Type",
            "idTyp": "0002",
            "idTypDesc": "UCM ID"
          }
        }
      ]
    },
    "PartySales": {
      "link": [],
      "firstRecord": 1,
      "pageSize": 10,
      "ST": "multi",
      "item": [
        {
          "rowidObject": "50505",
          "label": "Party Sales",
          "McaCntryCd": {
            "rowidObject": "14",
            "label": "Lookup Country",
            "cntryCd": "AU",
            "cntryDesc": "Australia"
          },
          "RegionCd": {
            "rowidObject": "2",
            "label": "LookupRegion Type Code",
            "RegionDesc": "APAC",
            "RegionCd": "0002"
          },
          "IbxRegionCd": {
            "rowidObject": "2",
            "label": "LookupRegion Type Code",
            "RegionDesc": "APAC",
            "RegionCd": "0002"
          }
        }
      ]
    },
    "PartyStatus": {
      "link": [],
      "firstRecord": 1,
      "pageSize": 10,
      "ST": "multi",
      "item": [
        {
          "rowidObject": "12880628",
          "label": "party Status",
          "RleStsTyp": {
            "rowidObject": "40001",
            "label": "Lookup Party Role Status Type",
            "prtyRleStsTyp": "0001",
            "prtyRleStsDesc": "Customer"
          },
          "RleStsVal": {
            "rowidObject": "1",
            "label": "Lookup Party Role Status Value",
            "prtyRleStsValDesc": "Active",
            "prtyRleStsVal": "0001"
          },
          "PrtyRleStgCd": {
            "rowidObject": "1",
            "label": "Lookup Party Stage Type",
            "PrtyRleStgTp": "0001",
            "PrtyRleStgDesc": "Order Booked"
          }
        }
      ]
    }
  }
}

Expected Output:

{
  "nenId": "OPER1006995",
  "MaskedFlg": true,
  "IsCustFlg": false,
  "$original": {
    "IsCustFlg": false,
    "MaskedFlg": false,
    "nenId": ""
  },
  "PartyStatus": {
    "item": [
      {
        "$original": {
          "RleStsVal": {},
          "PrtyRleStgCd": {}
        },
        "key": {
          "sourceKey": "1001",
          "rowid": "12880628"
        },
        "RleStsVal": {
          "prtyRleStsVal": "0001",
          "prtyRleStsTyp": "Active"
        },
        "PrtyRleStgCd": {
          "PrtyRleStgTp": "0002",
          "PrtyRleStgDesc": "Prospect"
        }
            }
        ],
    "$original": {
      "item": [
        {
          "rowid": "12880628"
                }
            ]
    }
  },
  "PartyAlternateId": {
    "item": [
      {
        "key": {
          "sourceKey": "1001", //id from input
          "rowid": "12880628" //rowidObject of the item whose gtResp "AltIdType.idTyp" 
                             //matches with input request obj "AltIdType.idTyp" 
        },
        "AltIdType": {
          "idTyp": "0001",
          "idTypDesc": "Account Number OU_NUM"
        },
        "AltIdVal": "104267367",
        "$original": {
          "AltIdVal": "",
          "EffStrtDt": "",
          "AltIdType": {}
        }
            },
      {
        "key": {
          "sourceKey": "1001",
          "rowid": "12880622"
        },
        "AltIdType": {
          "idTyp": "0002",
          "idTypDesc": "UCM ID"
        },
        "AltIdVal": "B99857DB-5B3C-469a-A976-F504AA74660A",
        "$original": {
          "AltIdVal": "",
          "EffStrtDt": "",
          "AltIdType": {}
        }
            }
        ],
    "$original": {
      "item": [
        {
          "rowid": "12880628"
                },
        {
          "rowid": "12880622"
                }
            ]
    }
  }
}

for the input json object, have to add $original object which will have all fields just like in input request object with values mapped from the gtresp object from the input. have to add “key” object which will contain sourceKey(value of id field) and rowId which contains the value of rowIdObject of the item whose “AltIdType.idTyp” matches with the input “AltIdType.idTyp” request object