Problem with type casting?

 The following is my extension method to cast types 
 
 public static T Cast<T>(this object obj)
 {
     return (T)obj;
 }
 
 This is my extension to convert list to array:
 
 public static List<Transform> ToTransformList(this List<WaypointData> waypointsDataList)
     {
         List<Transform> waypoints = new List<Transform>();
         foreach(WaypointData wd in waypointsDataList)
         {
             waypoints.Add(wd.waypoint);
         }
         return waypoints;
     }
 
 I use reflection and in that if i find any filled info of type list i need to convert it to array. The filed info
 
 FieldInfo[] fieldinfos = kamal.GetType ().GetFields();
         foreach(FieldInfo field in fieldinfos)
         try{
             if(field.FieldType.GetGenericTypeDefinition()==typeof(List<>))
             {
                                 //kamal actual type of List<String>//    
                     var cast = field.GetValue(kamal);
                                //here i need to make the program understand that this is some kind of list. Only then i can use my ToArray extension method. But the following is not working.
                    var array = cast.Cast<cast.GetType()>().ToArray();
             }
         }
         catch{}