Add RequestAttributeArgumentResolver

Closes gh-28458

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/support/WebClientAdapter.java

@@ -103,6 +103,7 @@ public class WebClientAdapter implements HttpClientAdapter {
 
 		bodySpec.headers(headers -> headers.putAll(requestValues.getHeaders()));
 		bodySpec.cookies(cookies -> cookies.putAll(requestValues.getCookies()));
+		bodySpec.attributes(attributes -> attributes.putAll(requestValues.getAttributes()));
 
 		if (requestValues.getBodyValue() != null) {
 			bodySpec.bodyValue(requestValues.getBodyValue());

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/support/WebClientHttpServiceProxyTests.java

@@ -19,6 +19,8 @@ package org.springframework.web.reactive.function.client.support;
 
 import java.io.IOException;
 import java.time.Duration;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.function.Consumer;
 
 import okhttp3.mockwebserver.MockResponse;
@@ -29,11 +31,13 @@ import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
 
-import org.springframework.http.client.reactive.ReactorClientHttpConnector;
+import org.springframework.web.bind.annotation.RequestAttribute;
 import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.service.annotation.GetExchange;
 import org.springframework.web.service.invoker.HttpServiceProxyFactory;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 
 /**
  * Integration tests for {@link HttpServiceProxyFactory HTTP Service proxy}
@@ -45,22 +49,10 @@ public class WebClientHttpServiceProxyTests {
 
 	private MockWebServer server;
 
-	private TestHttpService httpService;
-
 
 	@BeforeEach
 	void setUp() {
 		this.server = new MockWebServer();
-		WebClient webClient = WebClient
-				.builder()
-				.clientConnector(new ReactorClientHttpConnector())
-				.baseUrl(this.server.url("/").toString())
-				.build();
-
-		WebClientAdapter clientAdapter = new WebClientAdapter(webClient);
-		HttpServiceProxyFactory proxyFactory = HttpServiceProxyFactory.builder(clientAdapter).build();
-
-		this.httpService = proxyFactory.createClient(TestHttpService.class);
 	}
 
 	@SuppressWarnings("ConstantConditions")
@@ -78,12 +70,47 @@ public class WebClientHttpServiceProxyTests {
 		prepareResponse(response ->
 				response.setHeader("Content-Type", "text/plain").setBody("Hello Spring!"));
 
-		StepVerifier.create(this.httpService.getGreeting())
+		StepVerifier.create(initHttpService().getGreeting())
 				.expectNext("Hello Spring!")
 				.expectComplete()
 				.verify(Duration.ofSeconds(5));
 	}
 
+	@Test
+	void greetingWithRequestAttribute() {
+
+		Map<String, Object> attributes = new HashMap<>();
+
+		WebClient webClient = WebClient.builder()
+				.baseUrl(this.server.url("/").toString())
+				.filter((request, next) -> {
+					attributes.putAll(request.attributes());
+					return next.exchange(request);
+				})
+				.build();
+
+		prepareResponse(response ->
+				response.setHeader("Content-Type", "text/plain").setBody("Hello Spring!"));
+
+		StepVerifier.create(initHttpService(webClient).getGreetingWithAttribute("myAttributeValue"))
+				.expectNext("Hello Spring!")
+				.expectComplete()
+				.verify(Duration.ofSeconds(5));
+
+		assertThat(attributes).containsEntry("myAttribute", "myAttributeValue");
+	}
+
+	private TestHttpService initHttpService() {
+		WebClient webClient = WebClient.builder().baseUrl(this.server.url("/").toString()).build();
+		return initHttpService(webClient);
+	}
+
+	private TestHttpService initHttpService(WebClient webClient) {
+		WebClientAdapter clientAdapter = new WebClientAdapter(webClient);
+		HttpServiceProxyFactory proxyFactory = HttpServiceProxyFactory.builder(clientAdapter).build();
+		return proxyFactory.createClient(TestHttpService.class);
+	}
+
 	private void prepareResponse(Consumer<MockResponse> consumer) {
 		MockResponse response = new MockResponse();
 		consumer.accept(response);
@@ -96,6 +123,9 @@ public class WebClientHttpServiceProxyTests {
 		@GetExchange("/greeting")
 		Mono<String> getGreeting();
 
+		@GetExchange("/greeting")
+		Mono<String> getGreetingWithAttribute(@RequestAttribute String myAttribute);
+
 	}