HttpContext in EventReceiver constructor is null

I'm trying to use SPUtility.Redirect in ItemAdding EventReceiver. And I'm trying to get HttpContext.Current in Event Receiver constructor, but it's null

    public class MyClass : SPItemEventReceiver
    {

       HttpContext currentContext;

        public MyClass()
        {
               currentContext = HttpContext.Current; // is null
        }
     //.....
    }

Any ideas? SharePoint version is 2013.