warn("characters called with end < start");
warn("characters called with negative length");
    public void characters(char[] data, int start, int end) {        if (end > start)  {            String characterData = new String(data, start, end - start);            trace("characters:" + characterData);            if (currentElement == null) {                warn("Can't append text node to null currentElement");            } else {                Text textNode = currentDocument.createTextNode(characterData);                currentElement.appendChild(textNode);            }        } else {            warn("characters called with end < start");        }    }