code: @Override
  	protected Task<E> copyTo (Task<E> task) {
  		if (!lazy) throw new TaskCloneException("A non-lazy " + getClass().getSimpleName() + " should never be copied.");
  
  		Include<E> include = (Include<E>)task;
  		include.subtree = subtree;
  		include.lazy = lazy;
  
  		return task;
  	}
docs: Copies this {@code Include} to the given task. A {@link TaskCloneException} is thrown if this {@code Include} is eager.
  @param task the task to be filled
  @return the given task for chaining
  @throws TaskCloneException if this {@code Include} is eager.