Groovy script to identify transfer authority users during approval

I am attempting to have a groovy script identify if an approving user is approving for other users using transfer authority in Agile 9.3.4.  I am getting a null result.  Please review script below and provide feedback.

import com.agile.agileDSL.ScriptObj.IBaseScriptObj
import com.agile.agileDSL.ScriptObj.AgileDSLException
import com.agile.api.*
import com.agile.px.*

// This script should be executed with
//   Trigger Type = Pre
// Execution Mode = Synchronous
// Error Handling = Stop
// Event type = Approve for Workflow, Reject for Workflow

void invokeScript(IBaseScriptObj obj)
{
    IAgileSession session = obj.getAgileSDKSession()
    IEventInfo req = obj.getPXEventInfo()
    ISignOffEventInfo signoffeventinfo = (ISignOffEventInfo) req

//  See if user is using Transfer of Authority