code: public void trackGC(Object obj, String message){
          if(message==null)
              message = obj.getClass().getName()+'@'+System.identityHashCode(obj);
          track(obj, new MessagePrinter(message));
      }
docs: Prints {@code message} to {@code System.out} when {@code obj} gets garbage collected
  
  @param obj       object needs to be tracked
  @param message   message to be printed when {@code obj} gets garbage collected.
  if null, the message will be {@code obj.getClass().getName()+'@'+System.identityHashCode(obj)}