private static void rollback(ToggleStarRequest req) {
   if (req.getAddSet() != null) {
     for (Change.Id id : req.getAddSet()) {
       fireChangeStarEvent(id, false);
     }
   }
   if (req.getRemoveSet() != null) {
     for (Change.Id id : req.getRemoveSet()) {
       fireChangeStarEvent(id, true);
     }
   }
 }
 /**
  * Set the starred status of a change. This method broadcasts to all interested UI widgets and
  * sends an RPC to the server to record the updated status.
  */
 public static void toggleStar(final Change.Id changeId, final boolean newValue) {
   if (next == null) {
     next = new ToggleStarRequest();
   }
   next.toggle(changeId, newValue);
   fireChangeStarEvent(changeId, newValue);
   if (!busy) {
     start();
   }
 }