Sorry martin mistakenly i missed the no of line in the perivious code. I am attaching the code below.
RetailWebRequest request;
RetailWebResponse response;
str rawResponse;
RetailCommonWebAPI webApi;
Object deserializedContract;
List list;
ListIterator listIterator;
CreateCustGroupContract custGroupContract;
CustGroupList custGroupList;
webApi = RetailCommonWebAPI::construct();
request = RetailWebRequest::newUrl("URL");
response = webApi.getResponse(request);
rawResponse = response.parmData();
custGroupList = new TRICustGroupList();
list = new List(Types::String);
list.addEnd(rawResponse);
listIterator = new ListIterator(custGroupList.parmDataDetail(list));
while (listIterator.more())
{
custGroupContract = SMCFormJsonSerializer::deserializeObject(classIdGet(custGroupContract), listIterator.value());
info(strFmt('%1', custGroupContract.parmCustGroupId()));
info(custGroupContract.parmCustGroupName());
listIterator.next();
}
Json String returned in rawResponse like below

{
"success": true,
"data": [
{
"CUST_GROUP_ID": 1,
"CUST_GROUP_NAME": "Customer Group 1",
"INSERT_FLAG": "Y",
"RECORD_SENT_FLAG": "N",
"ERROR_MESSAGE": null,
"LAST_UPDATE_DATE": "2020-03-01T13:29:29.000Z",
"LAST_UPDATED_BY": 0,
"CREATION_DATE": "2020-03-01T13:29:29.000Z",
"CREATED_BY": 0
},
{
"CUST_GROUP_ID": 2,
"CUST_GROUP_NAME": "Customer Group 2",
"INSERT_FLAG": "Y",
"RECORD_SENT_FLAG": "N",
"ERROR_MESSAGE": null,
"LAST_UPDATE_DATE": "2020-03-01T13:29:29.000Z",
"LAST_UPDATED_BY": 0,
"CREATION_DATE": "2020-03-01T13:29:29.000Z",
"CREATED_BY": 0
}
]
}
Thanks,
Somesh