Rest Json Response, Need to get all the attribute key in the same order as in the response

That's a Map. It's just like an object in JSON. So for parsing a response, and checking the keys of the object, you would do something like this:

String response = '''{
    "DataValue": [
        {
            "ABC1": "Value",
            "ABC2": "Value"
        }, {
            "ABC1": "Value",
            "ABC2": "Value"
        }
    ]
}'''

new groovy.json.JsonSlurper().parseText(response)["DataValue"].each { dataValue ->

    ArrayList<String> keys = dataValue.collect { key, value -> key }
    assert keys == [ "ABC1", "ABC2" ]
    
}

And the assertion will fail if the order is different to what you are expecting.