WebClient exposes API for access to native request

Closes gh-25115, gh-25493

spring-web/src/main/java/org/springframework/http/client/reactive/ClientHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -47,4 +47,11 @@ public interface ClientHttpRequest extends ReactiveHttpOutputMessage {
 	 */
 	MultiValueMap<String, HttpCookie> getCookies();
 
+	/**
+	 * Return the request from the underlying HTTP library.
+	 * @param <T> the expected type of the request to cast to
+	 * @since 5.3
+	 */
+	<T> T getNativeRequest();
+
 }

spring-web/src/main/java/org/springframework/http/client/reactive/ClientHttpRequestDecorator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -80,6 +80,11 @@ public class ClientHttpRequestDecorator implements ClientHttpRequest {
 		return this.delegate.bufferFactory();
 	}
 
+	@Override
+	public <T> T getNativeRequest() {
+		return this.delegate.getNativeRequest();
+	}
+
 	@Override
 	public void beforeCommit(Supplier<? extends Mono<Void>> action) {
 		this.delegate.beforeCommit(action);

spring-web/src/main/java/org/springframework/http/client/reactive/HttpComponentsClientHttpRequest.java

@@ -94,6 +94,12 @@ class HttpComponentsClientHttpRequest extends AbstractClientHttpRequest {
 		return this.dataBufferFactory;
 	}
 
+	@Override
+	@SuppressWarnings("unchecked")
+	public <T> T getNativeRequest() {
+		return (T) this.httpRequest;
+	}
+
 	@Override
 	public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
 		return doCommit(() -> {

spring-web/src/main/java/org/springframework/http/client/reactive/JettyClientHttpRequest.java

@@ -84,6 +84,12 @@ class JettyClientHttpRequest extends AbstractClientHttpRequest {
 		return this.bufferFactory;
 	}
 
+	@Override
+	@SuppressWarnings("unchecked")
+	public <T> T getNativeRequest() {
+		return (T) this.jettyRequest;
+	}
+
 	@Override
 	public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
 		return Mono.<Void>create(sink -> {

spring-web/src/main/java/org/springframework/http/client/reactive/ReactorClientHttpRequest.java

@@ -64,11 +64,6 @@ class ReactorClientHttpRequest extends AbstractClientHttpRequest implements Zero
 	}
 
 
-	@Override
-	public DataBufferFactory bufferFactory() {
-		return this.bufferFactory;
-	}
-
 	@Override
 	public HttpMethod getMethod() {
 		return this.httpMethod;
@@ -79,6 +74,17 @@ class ReactorClientHttpRequest extends AbstractClientHttpRequest implements Zero
 		return this.uri;
 	}
 
+	@Override
+	public DataBufferFactory bufferFactory() {
+		return this.bufferFactory;
+	}
+
+	@Override
+	@SuppressWarnings("unchecked")
+	public <T> T getNativeRequest() {
+		return (T) this.request;
+	}
+
 	@Override
 	public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
 		return doCommit(() -> {