Initial HTTP/3 client support (#3319)

Related to #1531

docs/modules/ROOT/pages/http-client.adoc

@@ -336,6 +336,21 @@ include::{examples-dir}/http2/H2CApplication.java[lines=18..41]
 include::{sourcedir}/reactor/netty/http/HttpProtocol.java[lines=24..58]
 ----
 
+[[HTTP3]]
+== HTTP/3
+By default, the `HTTP` client supports `HTTP/1.1`. If you need `HTTP/3`, you can get it through configuration.
+In addition to the protocol configuration, you need to add dependency to `io.netty.incubator:netty-incubator-codec-http3`.
+
+The following listing presents a simple `HTTP3` example:
+
+{examples-link}/http3/Application.java
+----
+include::{examples-dir}/http3/Application.java[lines=18..49]
+----
+<1> Configures the client to support only `HTTP/3`
+<2> Configures `SSL`
+<3> Configures `HTTP/3` settings
+
 include::partial$proxy.adoc[]
 
 [[metrics]]

reactor-netty-examples/src/main/java/reactor/netty/examples/documentation/http/client/http3/Application.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2024 VMware, Inc. or its affiliates, All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package reactor.netty.examples.documentation.http.client.http3;
+
+import io.netty.handler.codec.http.HttpHeaders;
+import reactor.core.publisher.Mono;
+import reactor.netty.http.HttpProtocol;
+import reactor.netty.http.client.HttpClient;
+import reactor.util.function.Tuple2;
+
+import java.net.InetSocketAddress;
+import java.time.Duration;
+
+public class Application {
+
+	public static void main(String[] args) throws Exception {
+		HttpClient client =
+				HttpClient.create()
+				          .remoteAddress(() -> new InetSocketAddress("www.google.com", 443))
+				          .protocol(HttpProtocol.HTTP3)                                  //<1>
+				          .secure()                                                      //<2>
+				          .http3Settings(spec -> spec.idleTimeout(Duration.ofSeconds(5)) //<3>
+				                                     .maxData(10000000)
+				                                     .maxStreamDataBidirectionalLocal(1000000));
+
+		Tuple2<String, HttpHeaders> response =
+				client.get()
+				      .uri("/")
+				      .responseSingle((res, bytes) -> bytes.asString()
+				                                           .zipWith(Mono.just(res.responseHeaders())))
+				      .block();
+
+		System.out.println("Used stream ID: " + response.getT2().get("x-http3-stream-id"));
+		System.out.println("Response: " + response.getT1());
+	}
+}