code: public static String format(final String xml) {
          try {
              final DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
              final Document doc = db.parse(new InputSource(new StringReader(xml)));
              final Transformer transformer = TransformerFactory.newInstance().newTransformer();
              transformer.setOutputProperty(OutputKeys.INDENT, "yes");
              transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
              final StreamResult result = new StreamResult(new StringWriter());
              final DOMSource source = new DOMSource(doc);
              transformer.transform(source, result);
  
              return result.getWriter().toString();
          } catch (final Exception e) {
              LOGGER.log(Level.WARN, "Formats pretty XML failed: " + e.getMessage());
  
              return xml;
          }
      }
docs: Returns pretty print of the specified xml string.
  
  @param xml the specified xml string
  @return the pretty print of the specified xml string