code: public boolean preflightRequest() {
          final HttpURLConnection conn;
          try {
              final URL url = new URL(rootURL, "status");
              final URLConnectionFactory factory = new URLConnectionFactory(settings);
              conn = factory.createHttpURLConnection(url, useProxy);
              conn.addRequestProperty("Accept", "application/xml");
              final String authHeader = buildHttpAuthHeaderValue();
              if (!authHeader.isEmpty()) {
                  conn.addRequestProperty("Authorization", authHeader);
              }
              conn.connect();
              if (conn.getResponseCode() != 200) {
                  LOGGER.warn("Expected 200 result from Nexus, got {}", conn.getResponseCode());
                  return false;
              }
              final DocumentBuilder builder = XmlUtils.buildSecureDocumentBuilder();
  
              final Document doc = builder.parse(conn.getInputStream());
              if (!"status".equals(doc.getDocumentElement().getNodeName())) {
                  LOGGER.warn("Expected root node name of status, got {}", doc.getDocumentElement().getNodeName());
                  return false;
              }
          } catch (IOException | ParserConfigurationException | SAXException e) {
              return false;
          }
          return true;
      }
docs: Do a preflight request to see if the repository is actually working.
  
  @return whether the repository is listening and returns the /status URL
  correctly