Add ReactiveResponseConsumer classpath check to http5 auto-configuration

Closes gh-34964

Author: mhalbritter

spring-boot-project/spring-boot-autoconfigure/build.gradle

@@ -73,6 +73,7 @@ dependencies {
 		exclude group: "commons-logging", module: "commons-logging"
 	}
 	optional("org.apache.httpcomponents.client5:httpclient5")
+	optional("org.apache.httpcomponents.core5:httpcore5-reactive")
 	optional("org.apache.kafka:kafka-streams")
 	optional("org.apache.solr:solr-solrj") {
 		exclude group: "org.slf4j", module: "jcl-over-slf4j"
@@ -275,4 +276,4 @@ tasks.named("checkSpringConfigurationMetadata").configure {
 		"spring.datasource.tomcat.*",
 		"spring.groovy.template.configuration.*"
 	]
-}
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/reactive/function/client/ClientHttpConnectorConfiguration.java

@@ -18,6 +18,7 @@
 
 import org.apache.hc.client5.http.impl.async.HttpAsyncClients;
 import org.apache.hc.core5.http.nio.AsyncRequestProducer;
+import org.apache.hc.core5.reactive.ReactiveResponseConsumer;
 import org.eclipse.jetty.client.HttpClient;
 import org.eclipse.jetty.util.ssl.SslContextFactory;
 
@@ -87,7 +88,7 @@ JettyClientHttpConnector jettyClientHttpConnector(JettyResourceFactory jettyReso
 	}
 
 	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnClass({ HttpAsyncClients.class, AsyncRequestProducer.class })
+	@ConditionalOnClass({ HttpAsyncClients.class, AsyncRequestProducer.class, ReactiveResponseConsumer.class })
 	@ConditionalOnMissingBean(ClientHttpConnector.class)
 	static class HttpClient5 {
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/reactive/function/client/ClientHttpConnectorConfigurationTests.java

@@ -24,8 +24,10 @@
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.FilteredClassLoader;
 import org.springframework.boot.test.context.runner.ReactiveWebApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
+import org.springframework.http.client.reactive.HttpComponentsClientHttpConnector;
 import org.springframework.http.client.reactive.JettyClientHttpConnector;
 import org.springframework.http.client.reactive.JettyResourceFactory;
 import org.springframework.test.util.ReflectionTestUtils;
@@ -38,6 +40,7 @@
  *
  * @author Phillip Webb
  * @author Brian Clozel
+ * @author Moritz Halbritter
  */
 class ClientHttpConnectorConfigurationTests {
 
@@ -83,6 +86,14 @@ void shouldApplyHttpClientMapper() {
 			});
 	}
 
+	@Test
+	void shouldNotConfigureReactiveHttpClient5WhenHttpCore5ReactiveJarIsMissing() {
+		new ReactiveWebApplicationContextRunner()
+			.withClassLoader(new FilteredClassLoader("org.apache.hc.core5.reactive"))
+			.withConfiguration(AutoConfigurations.of(ClientHttpConnectorConfiguration.HttpClient5.class))
+			.run((context) -> assertThat(context).doesNotHaveBean(HttpComponentsClientHttpConnector.class));
+	}
+
 	static class CustomHttpClientMapper {
 
 		static boolean called = false;