docs: protected void performSubtasks(TaskRequest req, TaskResponse res, List<Task> tasks) {
          // Assertions...
          if (req == null) {
              String msg = "Argument 'req' cannot be null.";
              throw new IllegalArgumentException(msg);
          }
          if (res == null) {
              String msg = "Argument 'res' cannot be null.";
              throw new IllegalArgumentException(msg);
          }
          if (tasks == null) {
              String msg = "Child tasks have not been initialized.  Subclasses "
                              + "of AbstractContainerTask must call super.init() "
                              + "within their own init() method.";
              throw new IllegalStateException(msg);
          }
          
          // Invoke each of our children...
          for (Task k : tasks) {
              k.perform(req, res);
          }
  	}