Do not auto-configure HttpMessageConverters in reactive web apps

Closes gh-15712

Author: wilkinsona

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/HttpMessageConvertersAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -24,11 +24,16 @@
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication.Type;
+import org.springframework.boot.autoconfigure.condition.NoneNestedConditions;
 import org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration;
+import org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration.NotReactiveWebApplicationCondition;
 import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
 import org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.http.converter.HttpMessageConverter;
@@ -49,6 +54,7 @@
  */
 @Configuration
 @ConditionalOnClass(HttpMessageConverter.class)
+@Conditional(NotReactiveWebApplicationCondition.class)
 @AutoConfigureAfter({ GsonAutoConfiguration.class, JacksonAutoConfiguration.class,
 		JsonbAutoConfiguration.class })
 @Import({ JacksonHttpMessageConvertersConfiguration.class,
@@ -93,4 +99,17 @@ public StringHttpMessageConverter stringHttpMessageConverter() {
 
 	}
 
+	static class NotReactiveWebApplicationCondition extends NoneNestedConditions {
+
+		NotReactiveWebApplicationCondition() {
+			super(ConfigurationPhase.PARSE_CONFIGURATION);
+		}
+
+		@ConditionalOnWebApplication(type = Type.REACTIVE)
+		private static class ReactiveWebApplication {
+
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/http/HttpMessageConvertersAutoConfigurationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -32,6 +32,8 @@
 import org.springframework.boot.test.context.assertj.AssertableApplicationContext;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.boot.test.context.runner.ContextConsumer;
+import org.springframework.boot.test.context.runner.ReactiveWebApplicationContextRunner;
+import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.support.GenericApplicationContext;
@@ -257,6 +259,24 @@ public void jsonbIsPreferredIfJacksonAndGsonAreNotAvailable() {
 						"jsonbHttpMessageConverter"));
 	}
 
+	@Test
+	public void whenServletWebApplicationHttpMessageConvertersIsConfigured() {
+		new WebApplicationContextRunner()
+				.withConfiguration(AutoConfigurations
+						.of(HttpMessageConvertersAutoConfiguration.class))
+				.run((context) -> assertThat(context)
+						.hasSingleBean(HttpMessageConverters.class));
+	}
+
+	@Test
+	public void whenReactiveWebApplicationHttpMessageConvertersRestTemplateIsNotConfigured() {
+		new ReactiveWebApplicationContextRunner()
+				.withConfiguration(AutoConfigurations
+						.of(HttpMessageConvertersAutoConfiguration.class))
+				.run((context) -> assertThat(context)
+						.doesNotHaveBean(HttpMessageConverters.class));
+	}
+
 	private ApplicationContextRunner allOptionsRunner() {
 		return this.contextRunner
 				.withConfiguration(AutoConfigurations.of(GsonAutoConfiguration.class,