protected string ValueForHeader(string headerName)
        {
            string value;

            HeadersToSet.TryGetValue(headerName, out value);
            return(value);
        }
 protected void SetValueForHeader(string headerName, string value)
 {
     if (null == value)
     {
         HeadersToSet.Remove(headerName);
     }
     else
     {
         HeadersToSet[headerName] = value;
     }
 }