final Optional<ProxyOptions> proxyOptions = useSystemPropertiesProxyOptions();
if (proxyOptions.isPresent()) {
     final WebClientOptions webClientOptions = new WebClientOptions();
     webClientOptions.setProxyOptions(proxyOptions.get());
     client = WebClient.create(vertx, webClientOptions);
} else {
     client = WebClient.create(vertx);
}

private Optional<ProxyOptions> useSystemPropertiesProxyOptions() {
  final String httpsProxy = System.getProperty("https.proxyHost");
  if (httpsProxy != null) {
      return Optional.of(new ProxyOptions()
          .setHost(httpsProxy)
          .setPort(Integer.parseInt(System.getProperty("https.proxyPort", "443"))));
  } else {
       final String httpProxy = System.getProperty("http.proxyHost");
       if (httpProxy != null) {
           return Optional.of(new ProxyOptions()
               .setHost(httpsProxy)
               .setPort(Integer.parseInt(System.getProperty("http.proxyPort", "80"))));
       }
  }
  return Optional.empty();
}