### Question:
XMLUtils { public static String removeInvalidXMLChars(String text) { if (text == null || text.isEmpty()) { return text; } return text.replaceAll(INVALID_XML_CHARACTERS, ""); }  String getATTR_VALUE_PAIR_NODE(); static boolean isValidating(); static Document toDOMDocument(String xmlString, Debug debug); static Document toDOMDocument(InputStream is, Debug debug); static Set parseAttributesTag(Node n); static Map<String, Set<String>> parseAttributeValuePairTags(Node parentNode); static Document newDocument(); static Document getXMLDocument(InputStream in); static Node getRootNode(Document doc, String nodeName); static Node getChildNode(Node parentNode, String childName); static boolean hasElementChild(Node node); static Node getNamedChildNode(Node parentNode, String childNodeName,
            String attrName, String attrValue); static Set getChildNodes(Node parentNode, String childName); static String getElementValue(Element element); static String getChildrenValue(Element element); static String getElementString(Element element); static String getNodeAttributeValue(Node node, String attrName); static String getNodeAttributeValueNS(Node node,
            String namespaceURI, String attrName); static Set getAttributeValuePair(Node node); static Set getAttributeValuePair(Node node, boolean unescape); static String getValueOfValueNode(Node n); static String getValueOfValueNode(Node n, boolean unescape); static String getValueOfValueNodeNoTrim(Node n); static String getValueOfValueNodeNoTrim(Node n, boolean unescape); static List getElementsByTagNameNS1(
        Element element,
        String nsName,
        String tagName
    ); static String printAttributeValue(Element node, String prefix); static String print(Node node); static String print(Node node, String encoding); static String unescapeSpecialCharacters(String text); static String escapeSpecialCharacters(String text); static String removeInvalidXMLChars(String text); static Set encodeAttributeSet(Set set, Debug debug); static Set decodeAttributeSet(Set set); static String removeNullCharAtEnd(String st); static DocumentBuilder getSafeDocumentBuilder(boolean validating); static SAXParser getSafeSAXParser(boolean validating); static TransformerFactory getTransformerFactory(); static SAXSource createSAXSource(InputSource source);  }### Answer:
@Test(dataProvider = "invalid") public void invalidCharactersAreCorrectlyRemoved(String invalid) { assertThat(XMLUtils.removeInvalidXMLChars(invalid)).isEqualTo("helloworld"); }