docs: @Override
      public void startElement(final String uri, final String localName, final String name,
              final Attributes atts) throws SAXException {
          if (ignoreDepth > 0) {
              ignoreDepth++;
              return;
          }
  
          if (PR_D_CODEREF.matches(atts)) {
              ignoreDepth++;
              try {
                  final URI hrefValue = toURI(atts.getValue(ATTRIBUTE_NAME_HREF));
                  if (hrefValue != null) {
                      final File codeFile = getFile(hrefValue);
                      if (codeFile != null && codeFile.exists()) {
                          logger.debug("Resolve coderef " + codeFile);
                          final Charset charset = getCharset(atts.getValue(ATTRIBUTE_NAME_FORMAT));
                          final Range range = getRange(hrefValue);
                          try (BufferedReader codeReader = new BufferedReader(
                                  new InputStreamReader(new FileInputStream(codeFile), charset))) {
                              range.copyLines(codeReader);
                          } catch (final Exception e) {
                              logger.error("Failed to process code reference " + codeFile, e);
                          }
                      } else {
                          logger.warn(MessageUtils.getMessage("DOTJ051E", hrefValue.toString()).setLocation(atts).toString());
                      }
                  } else {
                      //logger.logDebug("Code reference target not defined");
                  }
              } catch (final Exception e) {
                  logger.error(e.getMessage(), e) ;
              }
          } else {
              super.startElement(uri, localName, name, atts);
          }
      }