Add http3 module: HTTP/3 in the Java HTTP Client (JEP 517), opt-in, discovery modes, fallback timings, proxy downgrade and a packet-loss comparison

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01KqJyCidz3ZgRyHABv2GVJh

http3/src/Tls.java

@@ -0,0 +1,26 @@
+import java.io.FileInputStream;
+import java.net.http.HttpClient;
+import java.security.KeyStore;
+import java.security.cert.CertificateFactory;
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.TrustManagerFactory;
+
+/** Trusts only the self-signed test certificate in certs/cert.pem (made by server/make-cert.sh). */
+final class Tls {
+    static SSLContext context() throws Exception {
+        KeyStore ks = KeyStore.getInstance("PKCS12");
+        ks.load(null);
+        try (var in = new FileInputStream("certs/cert.pem")) {
+            ks.setCertificateEntry("test", CertificateFactory.getInstance("X.509").generateCertificate(in));
+        }
+        TrustManagerFactory tmf = TrustManagerFactory.getInstance("PKIX");
+        tmf.init(ks);
+        SSLContext ctx = SSLContext.getInstance("TLS");
+        ctx.init(null, tmf.getTrustManagers(), null);
+        return ctx;
+    }
+
+    static HttpClient.Builder builder() throws Exception {
+        return HttpClient.newBuilder().sslContext(context());
+    }
+}