code: public ArrayList<STUNService> loadSTUNServers() {
          ArrayList<STUNService> serversList = new ArrayList<>();
  
          // Load the STUN configuration
          try {
              // Get an array of class loaders to try loading the config from.
              ClassLoader[] classLoaders = new ClassLoader[2];
              classLoaders[0] = new STUNResolver() {
              }.getClass().getClassLoader();
              classLoaders[1] = Thread.currentThread().getContextClassLoader();
  
              for (int i = 0; i < classLoaders.length; i++) {
                  Enumeration<URL> stunConfigEnum = classLoaders[i]
                          .getResources(STUNSERVERS_FILENAME);
  
                  while (stunConfigEnum.hasMoreElements() && serversList.isEmpty()) {
                      URL url = stunConfigEnum.nextElement();
                      java.io.InputStream stunConfigStream;
  
                      stunConfigStream = url.openStream();
                      serversList.addAll(loadSTUNServers(stunConfigStream));
                      stunConfigStream.close();
                  }
              }
          }
          catch (Exception e) {
              LOGGER.log(Level.SEVERE, "Exception", e);
          }
  
          return serversList;
      }
docs: Load a list of services: STUN servers and ports. Some public STUN servers
  are:
  
  <pre>
  iphone-stun.freenet.de:3478
  larry.gloo.net:3478
  stun.xten.net:3478
  stun.fwdnet.net
  stun.fwd.org (no DNS SRV record)
  stun01.sipphone.com (no DNS SRV record)
  stun.softjoys.com (no DNS SRV record)
  stun.voipbuster.com (no DNS SRV record)
  stun.voxgratia.org (no DNS SRV record)
  stun.noc.ams-ix.net
  </pre>
  
  This list should be contained in a file in the "META-INF" directory
  
  @return a list of services