//Name 	 set_actual_start
//Description 	Sets the value of the actual start date as date/time on which the first "Started work" message was created.
//Type 	Task / Custom Field Value

if (task.getMessages()!=null){
  Object list = task.getMessages();
  for (int j=task.getMessageCount(); j>0; j--){
    Object message = list.get(j-1);
    if (message.getMstatus().getName().equals("Started work")){
      return message.getTime();
      break;
    }
  }
}
return null;