Change Request owner

Anyone know how to change the __Legacy.Workflow.User property?

setting either or both __Legacy.Workflow.User __Legacy.Workflow.ImpersonatingUser has no effect

Using vCO SDK to request catalog item.

                string attributes;

                attributes = "TotalStorageSize,string," + storage;

                attributes += ",DNSServer,string," + domainController;

                attributes += ",DNSZone,string," + domain;

                attributes += ",ServerDomain,string," + domainPrefix;

                attributes += ",ServerHostName,string," + hostName;

                attributes += ",ServerType,string," + serverType;

                attributes += ",isDMZ,string," + isDMZ;

                attributes += ",AdMachineCleanupDomain,string," + domainController;

                attributes += ",VirtualMachineCPUCount,string," + cpuCount;

                attributes += ",disks,string," + disks;

                attributes += ",VirtualMachineMemorySize,string," + memory;

                attributes += ",VirtualMachineNetwork0ProfileName,string," + vlan;

                attributes += ",__request_reason,string," + __request_reason;

                attributes += ",provisioningGroupId,string," + PRE_provisioningGroupId;

                attributes += ",item,vCACCAFE:CatalogItem," + dunes_blueprintURI;

                attributes += ",requestor,string," + requestor;

                WorkflowToken wfToken = new WorkflowToken();

                wfToken = vCO.ExecuteWorkflow("33295b30-24e5-4938-be99-7168ac0ca05c", vCACAdminUser, vCACAdminPW, attributes);

In the workflow I am setting

var jsRequestor = { name: "provider-__Legacy.Workflow.ImpersonatingUser", value: requestor};

param.push(jsRequestor);

var jsRequestor2 = { name: "provider-__Legacy.Workflow.User", value: requestor};

param.push(jsRequestor2);