public static void SetCustomAttribute()
{
string url = string.Format("http://ap-fvzlpv2:13490/agilepointserver/workflow/SetCustomAttrs/{0}", "4C04E35AD1914CD69A1A68D5AB52DB4C");
WebHeaderCollection headerCollection = new WebHeaderCollection();
headerCollection.Add("Authorization", AuthHeader);
List <NameValue> list = new List <NameValue>();
list.Add(new NameValue("/pd:AP/pd:processFields/pd:text1", "Value1"));
CustAttributeRequest custAttributeRequest = new CustAttributeRequest();
custAttributeRequest.attributes = list;
string payload = JsonConvert.SerializeObject(custAttributeRequest);
string Response = RestUtility.MakeRESTHTTPRequest(url, System.Net.Http.HttpMethod.Post, headerCollection, payload, "application/json");
// ManualWorkItemResponse manualWorkItemResponse = JsonConvert.DeserializeObject<ManualWorkItemResponse>(Response);
}