Value returns null after passing from javascript to Modify action class in struts

Question

This dropdown element will call this javascript function

function updateFields(val) {

        var objData = new kendo.data.DataSource({
            transport : {
                read : {
                    url : "Modify.do?command.do(getInfo)",
                    dataType : "json",
                    cache : false,
                    beforeSend : function(req) {
                        req.setRequestHeader('isAjaxRequest', "true");
                    }
                },

                parameterMap : function(data, action) {
                    if (action === "read") {
                        var stateId = $("#sending").val();
                        console.log('----'+ id);
                        return "req-id=" + id;
                        
                    } else {

                        return data;
                    }
                }
            },

        });

Was able to call this Modify Action class and try getting the id via request get attribute but the value returns null.

Long Id = (Long) request.getAttribute("id");