@Override
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        if (contentHandler == null) {
            return;
        }
        if (isWalkOver) {
            contentHandler.characters(ch, start, length);
            return;
        }

        if (inHeadingContentOrHiddenElement && !inHiddenSubtree()) {
            currentSection.getHeadingTextBuilder().append(ch, start, length);
        }
        contentHandler.characters(ch, start, length);
    }
@see org.xml.sax.helpers.XMLFilterImpl#characters(char[], int, int)
src/nu/validator/servlet/OutlineBuildingXMLReaderWrapper.java