#vulnerable code 
                             @Override
	protected void doUnmarshalValue(Element element, VCardVersion version, List<String> warnings, CompatibilityMode compatibilityMode) throws VCardException {
		Element ele = XCardUtils.getFirstElement(element.getChildNodes());
		value = ele.getTextContent();
		if (value.matches("(?i)tel:.*")) {
			//remove "tel:"
			value = (value.length() > 4) ? value.substring(4) : "";
		}
	} 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             @Override
	protected void doUnmarshalValue(Element element, VCardVersion version, List<String> warnings, CompatibilityMode compatibilityMode) throws VCardException {
		String value = XCardUtils.getFirstChildText(element, "text", "uri");
		if (value != null) {
			parseValue(value);
		}
	}