Refine solution to clear Netty channel attribute

Closes gh-36158

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

@@ -21,14 +21,12 @@ import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Function;
 
-import io.netty.channel.Channel;
-import io.netty.util.Attribute;
 import io.netty.util.AttributeKey;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import reactor.core.publisher.Mono;
+import reactor.netty.Connection;
 import reactor.netty.NettyOutbound;
-import reactor.netty.channel.ChannelOperations;
 import reactor.netty.http.client.HttpClient;
 import reactor.netty.http.client.HttpClientRequest;
 import reactor.netty.resources.ConnectionProvider;
@@ -166,17 +164,15 @@ public class ReactorClientHttpConnector implements ClientHttpConnector, SmartLif
 				.request(io.netty.handler.codec.http.HttpMethod.valueOf(method.name()));
 
 		requestSender = setUri(requestSender, uri);
-		AtomicReference<Channel> channelRef = new AtomicReference<>();
 		AtomicReference<ReactorClientHttpResponse> responseRef = new AtomicReference<>();
 
 		return requestSender
-				.send((request, outbound) -> {
-					channelRef.set(((ChannelOperations<?, ?>) request).channel());
-					return requestCallback.apply(adaptRequest(method, uri, request, outbound));
-				})
+				.send((request, outbound) -> requestCallback.apply(adaptRequest(method, uri, request, outbound)))
 				.responseConnection((response, connection) -> {
-					responseRef.set(new ReactorClientHttpResponse(response, connection));
-					return Mono.just((ClientHttpResponse) responseRef.get());
+					ReactorClientHttpResponse clientResponse = new ReactorClientHttpResponse(response, connection);
+					responseRef.set(clientResponse);
+					clearChannelAttribute(connection);
+					return Mono.just((ClientHttpResponse) clientResponse);
 				})
 				.next()
 				.doOnCancel(() -> {
@@ -184,15 +180,6 @@ public class ReactorClientHttpConnector implements ClientHttpConnector, SmartLif
 					if (response != null) {
 						response.releaseAfterCancel(method);
 					}
-				})
-				.doOnTerminate(() -> {
-					Channel channel = channelRef.get();
-					if (channel != null) {
-						Attribute<Map<String, Object>> attribute = channel.attr(ATTRIBUTES_KEY);
-						if (attribute != null) {
-							attribute.set(null);
-						}
-					}
 				});
 	}
 
@@ -214,6 +201,15 @@ public class ReactorClientHttpConnector implements ClientHttpConnector, SmartLif
 		return new ReactorClientHttpRequest(method, uri, request, nettyOutbound);
 	}
 
+	private static void clearChannelAttribute(Connection connection) {
+		connection.onTerminate().subscribe(
+				aVoid -> {}, ex -> clearAttribute(connection), () -> clearAttribute(connection));
+	}
+
+	private static void clearAttribute(Connection connection) {
+		connection.channel().attr(ATTRIBUTES_KEY).set(null);
+	}
+
 
 	@Override
 	public void start() {