#vulnerable code 
                              public void start(final InetAddress... bindAddresses) throws IOException {
    start(bindAddresses, Constants.DEFAULT_ANNOUNCE_INTERVAL_SEC, null);
  } 
                            #location 2 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              public void start(final InetAddress... bindAddresses) throws IOException {
    start(bindAddresses, Constants.DEFAULT_ANNOUNCE_INTERVAL_SEC, null, new SelectorFactoryImpl());
  }