code: public void bind(ServerSocketBar ss)
      throws IOException
    {
      Objects.requireNonNull(ss);
  
      _isBind.set(true);
  
      if (_protocol == null)
        throw new IllegalStateException(L.l("'{0}' must have a configured protocol before starting.", this));
  
      if (_throttle == null)
        _throttle = new ThrottleSocket();
  
      _serverSocket = ss;
  
      String scheme = _protocol.name();
  
      if (_address != null)
        log.info(scheme + " listening to " + _address + ":" + _port);
      else
        log.info(scheme + " listening to *:" + _port);
  
      if (_sslFactory != null) {
        try {
          _serverSocket = _sslFactory.bind(_serverSocket);
        } catch (RuntimeException e) {
          throw e;
        } catch (IOException e) {
          throw e;
        } catch (Exception e) {
          throw new IOException(e);
        }
      }
    }
docs: Starts the port listening.