From 0241a02e66f56623877f5bc8d91684d8d315cb97 Mon Sep 17 00:00:00 2001
From: Arjen Poutsma <arjen.poutsma@broadcom.com>
Date: Tue, 30 Apr 2024 11:49:15 +0200
Subject: [PATCH 1/2] Fix guard against multiple subscriptions

This commit changes the guard against multiple subscriptions, as the
previously used doOnSubscribe hook could not function as guard in
certain scenarios.

Closes gh-32727
---
 .../reactive/AbstractClientHttpResponse.java  | 50 +++++++++++++++----
 1 file changed, 40 insertions(+), 10 deletions(-)

diff --git a/spring-web/src/main/java/org/springframework/http/client/reactive/AbstractClientHttpResponse.java b/spring-web/src/main/java/org/springframework/http/client/reactive/AbstractClientHttpResponse.java
index 4b128b04748..60cf8b73f61 100644
--- a/spring-web/src/main/java/org/springframework/http/client/reactive/AbstractClientHttpResponse.java
+++ b/spring-web/src/main/java/org/springframework/http/client/reactive/AbstractClientHttpResponse.java
@@ -16,8 +16,12 @@
 
 package org.springframework.http.client.reactive;
 
+import java.util.Objects;
 import java.util.concurrent.atomic.AtomicBoolean;
 
+import org.reactivestreams.Publisher;
+import org.reactivestreams.Subscriber;
+import org.reactivestreams.Subscription;
 import reactor.core.publisher.Flux;
 
 import org.springframework.core.io.buffer.DataBuffer;
@@ -55,16 +59,7 @@ public abstract class AbstractClientHttpResponse implements ClientHttpResponse {
 		this.statusCode = statusCode;
 		this.headers = headers;
 		this.cookies = cookies;
-		this.body = singleSubscription(body);
-	}
-
-	private static Flux<DataBuffer> singleSubscription(Flux<DataBuffer> body) {
-		AtomicBoolean subscribed = new AtomicBoolean();
-		return body.doOnSubscribe(s -> {
-			if (!subscribed.compareAndSet(false, true)) {
-				throw new IllegalStateException("The client response body can only be consumed once");
-			}
-		});
+		this.body = Flux.from(new SingleSubscriberPublisher<>(body));
 	}
 
 
@@ -87,4 +82,39 @@ public abstract class AbstractClientHttpResponse implements ClientHttpResponse {
 	public Flux<DataBuffer> getBody() {
 		return this.body;
 	}
+
+
+	private static final class SingleSubscriberPublisher<T> implements Publisher<T> {
+
+		private static final Subscription NO_OP_SUBSCRIPTION = new Subscription() {
+			@Override
+			public void request(long l) {
+			}
+
+			@Override
+			public void cancel() {
+			}
+		};
+
+		private final Publisher<T> delegate;
+
+		private final AtomicBoolean subscribed = new AtomicBoolean();
+
+
+		public SingleSubscriberPublisher(Publisher<T> delegate) {
+			this.delegate = delegate;
+		}
+
+		@Override
+		public void subscribe(Subscriber<? super T> subscriber) {
+			Objects.requireNonNull(subscriber, "Subscriber must not be null");
+			if (this.subscribed.compareAndSet(false, true)) {
+				this.delegate.subscribe(subscriber);
+			}
+			else {
+				subscriber.onSubscribe(NO_OP_SUBSCRIPTION);
+				subscriber.onError(new IllegalStateException("The client response body can only be consumed once"));
+			}
+		}
+	}
 }

From 32c80d5ae6629f86cd7c29cbb054e5175805f4cf Mon Sep 17 00:00:00 2001
From: Seungrae Kim <obey1342@gmail.com>
Date: Tue, 30 Apr 2024 21:30:39 +0900
Subject: [PATCH 2/2] Fix incorrect class reference syntax in Kotlin code
 sample

Closes gh-32733
---
 .../modules/ROOT/pages/testing/webtestclient.adoc           | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/framework-docs/modules/ROOT/pages/testing/webtestclient.adoc b/framework-docs/modules/ROOT/pages/testing/webtestclient.adoc
index cd625209b35..3a4713b1332 100644
--- a/framework-docs/modules/ROOT/pages/testing/webtestclient.adoc
+++ b/framework-docs/modules/ROOT/pages/testing/webtestclient.adoc
@@ -672,13 +672,13 @@ Kotlin::
 	val result = client.get().uri("/persons/1")
 			.exchange()
 			.expectStatus().isOk()
-			.expectBody(Person.class)
-			.returnResult();
+			.expectBody(Person::class.java)
+			.returnResult()
 
 	// For a response without a body
 	val result = client.get().uri("/path")
 			.exchange()
-			.expectBody().isEmpty();
+			.expectBody().isEmpty()
 ----
 ======