http to https redirect with Spring Cloud Gateway

HttpToHttpsRedirectConfig.java

package com.bjoernkw.gateway;

@Configuration
public class HttpToHttpsRedirectConfig {    
    
    @Value("${server.port}")
    private Integer gatewayPort;

    @PostConstruct
    public WebServerFactoryCustomizer serverFactoryCustomizer() {
        return new NettyHttpCustomizer();
    }

    private class NettyHttpCustomizer implements WebServerFactoryCustomizer<NettyReactiveWebServerFactory> {
        @Override
        public void customize(NettyReactiveWebServerFactory httpNettyReactiveWebServerFactory) {
            httpNettyReactiveWebServerFactory.getWebServer((request, response) -> {
                URI uri = request.getURI();
                URI httpsUri;

                try {
                    httpsUri = new URI("https", uri.getUserInfo(), uri.getHost(), gatewayPort, uri.getPath(), uri.getQuery(), uri.getFragment());
                } catch (URISyntaxException e) {
                    return Mono.error(e);
                }

                response.setStatusCode(HttpStatus.MOVED_PERMANENTLY);
                response.getHeaders().setLocation(httpsUri);

                return response.setComplete();
            }).start();
        }
    }
}