code: @Override
  	public Set<T> getAllChildNodes() {
  
  		Set<T> allChildNodes = new HashSet();
  
  		List<T> childNodes = treeGetChildren();
  
  		for (final T child : childNodes) {
  
  			allChildNodes.add(child);
  
  			if (child instanceof LinkedTreeNode) {
  
  				final LinkedTreeNode treeNode = (LinkedTreeNode)child;
  				allChildNodes.addAll(treeNode.getAllChildNodes());
  			}
  		}
  
  		return allChildNodes;
  	}
docs: Return a set containing all child nodes of this node.
  
  This node is not included.
  There are no duplicates.
  
  @return child nodes