code: func (s *StanServer) configureNATSServerTLS() error {
  	opts := s.natsOpts
  	tlsSet := false
  	tc := server.TLSConfigOpts{}
  	if opts.TLSCert != "" {
  		tc.CertFile = opts.TLSCert
  		tlsSet = true
  	}
  	if opts.TLSKey != "" {
  		tc.KeyFile = opts.TLSKey
  		tlsSet = true
  	}
  	if opts.TLSCaCert != "" {
  		tc.CaFile = opts.TLSCaCert
  		tlsSet = true
  	}
  
  	if opts.TLSVerify {
  		tc.Verify = true
  		tlsSet = true
  	}
  
  	var err error
  	if tlsSet {
  		if opts.TLSConfig, err = server.GenTLSConfig(&tc); err != nil {
  			// The connection will fail later if the problem is severe enough.
  			return fmt.Errorf("unable to setup NATS Server TLS:  %v", err)
  		}
  	}
  	return nil
  }
docs: // configureNATSServerTLS sets up TLS for the NATS Server.
  // Additional TLS parameters (e.g. cipher suites) will need to be placed
  // in a configuration file specified through the -config parameter.