Make it easier to override RequestToViewNameTranslator bean

See gh-40874

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.java

@@ -95,6 +95,7 @@ import org.springframework.web.servlet.DispatcherServlet;
 import org.springframework.web.servlet.FlashMapManager;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.LocaleResolver;
+import org.springframework.web.servlet.RequestToViewNameTranslator;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.config.annotation.AsyncSupportConfigurer;
@@ -469,6 +470,15 @@ public class WebMvcAutoConfiguration {
 			return super.flashMapManager();
 		}
 
+
+		@Override
+		@Bean
+		@ConditionalOnMissingBean(name = DispatcherServlet.REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME)
+		public RequestToViewNameTranslator viewNameTranslator() {
+			return super.viewNameTranslator();
+		}
+
+
 		private Resource getIndexHtmlResource() {
 			for (String location : this.resourceProperties.getStaticLocations()) {
 				Resource indexHtml = getIndexHtmlResource(location);

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java

@@ -65,6 +65,7 @@ import org.springframework.boot.web.servlet.context.AnnotationConfigServletWebSe
 import org.springframework.boot.web.servlet.filter.OrderedFormContentFilter;
 import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
 import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
@@ -89,6 +90,7 @@ import org.springframework.web.accept.ContentNegotiationManager;
 import org.springframework.web.accept.ParameterContentNegotiationStrategy;
 import org.springframework.web.bind.annotation.ControllerAdvice;
 import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
+import org.springframework.web.context.request.RequestAttributes;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
 import org.springframework.web.filter.FormContentFilter;
@@ -102,6 +104,7 @@ import org.springframework.web.servlet.HandlerAdapter;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.HandlerMapping;
 import org.springframework.web.servlet.LocaleResolver;
+import org.springframework.web.servlet.RequestToViewNameTranslator;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.config.annotation.AsyncSupportConfigurer;
@@ -404,6 +407,24 @@ class WebMvcAutoConfigurationTests {
 			});
 	}
 
+	@Test
+	public void customViewNameTranslatorWithDifferentNameDoesNotReplaceDefaultViewNameTranslator() {
+		this.contextRunner.withBean("viewNameTranslator", CustomViewNameTranslator.class, CustomViewNameTranslator::new)
+			.run((context) -> {
+				assertThat(context.getBean("customViewNameTranslator")).isInstanceOf(CustomViewNameTranslator.class);
+				assertThat(context.getBean("viewNameTranslator")).isInstanceOf(SessionFlashMapManager.class);
+			});
+	}
+
+	@Test
+	void customViewNameTranslatorWithDifferentNameReplaceDefaultViewNameTranslator() {
+		this.contextRunner.withBean("viewNameTranslator", CustomViewNameTranslator.class, CustomViewNameTranslator::new)
+				.run((context) -> {
+					assertThat(context).hasSingleBean(RequestToViewNameTranslator.class);
+					assertThat(context.getBean("viewNameTranslator")).isInstanceOf(CustomViewNameTranslator.class);
+				});
+	}
+
 	@Test
 	void defaultDateFormat() {
 		this.contextRunner.run((context) -> {
@@ -1458,6 +1479,15 @@ class WebMvcAutoConfigurationTests {
 
 	}
 
+	static class CustomViewNameTranslator implements RequestToViewNameTranslator {
+
+		@Override
+		public String getViewName(HttpServletRequest requestAttributes) {
+			return null;
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class ResourceHandlersWithChildAndParentContextConfiguration {