Helidon SE Java

import io.helidon.http.HeaderNames;
import io.helidon.webserver.WebServer;
import java.util.Base64;

public class Pixel {

    private static final byte[] GIF = Base64.getDecoder().decode("R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==");

    public static void main(String[] args) {
        WebServer.builder()
                .port(8080)
                .routing(routing -> routing.get("/pixel.gif", (req, res) -> {
                    res.header(HeaderNames.CONTENT_TYPE, "image/gif");
                    res.header(HeaderNames.CACHE_CONTROL, "no-store");
                    res.send(GIF);
                }))
                .build()
                .start();
    }
}