Single Class Java HTTP Client with Proxy and SSL/TLS Keystore Settings

import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManagerFactory;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ProxySelector;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpRequest.BodyPublishers;
import java.net.http.HttpResponse;
import java.net.http.HttpResponse.BodyHandlers;
import java.security.KeyManagementException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.UnrecoverableKeyException;
import java.security.cert.CertificateException;
import java.time.Duration;
import java.time.temporal.ChronoUnit;

public class HttpTest {
    public static void main(String[] args)
        throws URISyntaxException, NoSuchAlgorithmException, KeyManagementException, KeyStoreException, UnrecoverableKeyException, IOException, CertificateException {
        String bodyPayload = """
            ourpayload, json, xml, ...
            """;

        String keyStorePath = "/opt/keystore.jks";
        String keyStorePassword = "ABCDEFG";

        String proxyHost = "ourproxy.proxy";
        String uriString = "https://some-service/api";
        int proxyPort = 8080;
        int timeoutInSeconds = 60;

        KeyStore keyStore = KeyStore.getInstance("JKS");
        keyStore.load(new FileInputStream(keyStorePath), keyStorePassword.toCharArray());

        KeyManagerFactory keyManagerFactory = KeyManagerFactory.getInstance("PKIX");
        keyManagerFactory.init(keyStore, null);

        TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance("PKIX"); // using same keystore for both
        trustManagerFactory.init(keyStore);

        SSLContext sslContext = SSLContext.getInstance("TLS");
        sslContext.init(keyManagerFactory.getKeyManagers(), trustManagerFactory.getTrustManagers(), null);

        HttpClient client = HttpClient.newBuilder()
                                      .proxy(
                                          ProxySelector.of(new InetSocketAddress(proxyHost, proxyPort)))
                                      .sslContext(sslContext)
                                      .build();
        URI uri = new URI(uriString);
        HttpRequest request = HttpRequest.newBuilder(uri)
                                         .POST(BodyPublishers.ofString(bodyPayload))
                                         .timeout(Duration.of(timeoutInSeconds, ChronoUnit.SECONDS))
                                         .build();
        System.out.printf("Sending POST request to %s, timeout: %ds%n", uri, timeoutInSeconds);
        try {
            HttpResponse response = client.send(request, BodyHandlers.ofString());
            System.out.println("Response received...");
            System.out.printf("\tResponse-Status: %d%n", response.statusCode());
            System.out.printf("\tResponse-Body: %s%n", response.body());
            System.out.println("-------------------------------------%n");

        } catch (IOException e) {
            System.err.printf("IOException caught: %s%n", e.getMessage());
            e.printStackTrace(System.err);
        } catch (InterruptedException e) {
            System.err.printf("IOException caught: %s%n", e.getMessage());
            e.printStackTrace(System.err);
        }
    }
}

cat << EOF > HttpTest.java && javac HttpTest.java && java HttpTest
<PASTE>
EOF