Remove default favicon and support for serving from classpath root

Closes gh-17925

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

@@ -332,27 +332,6 @@ public class WebMvcAutoConfiguration {
 			return new OrderedRequestContextFilter();
 		}
 
-		@Configuration(proxyBeanMethods = false)
-		@ConditionalOnProperty(value = "spring.mvc.favicon.enabled", matchIfMissing = true)
-		public static class FaviconConfiguration implements WebMvcConfigurer {
-
-			private final ResourceProperties resourceProperties;
-
-			FaviconConfiguration(ResourceProperties resourceProperties) {
-				this.resourceProperties = resourceProperties;
-			}
-
-			@Override
-			public void addResourceHandlers(ResourceHandlerRegistry registry) {
-				if (!registry.hasMappingForPattern("favicon.ico")) {
-					registry.addResourceHandler("favicon.ico")
-							.addResourceLocations(this.resourceProperties.getStaticLocations())
-							.addResourceLocations("classpath:favicon.ico");
-				}
-			}
-
-		}
-
 	}
 
 	/**

spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -699,12 +699,6 @@
       "name": "spring.mustache.suffix",
       "defaultValue": ".mustache"
     },
-    {
-      "name": "spring.mvc.favicon.enabled",
-      "type": "java.lang.Boolean",
-      "description": "Whether to enable resolution of favicon.ico.",
-      "defaultValue": true
-    },
     {
       "name": "spring.mvc.formcontent.putfilter.enabled",
       "type": "java.lang.Boolean",

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

@@ -196,7 +196,7 @@ class WebMvcAutoConfigurationTests {
 	@Test
 	void resourceHandlerMappingDisabled() {
 		this.contextRunner.withPropertyValues("spring.resources.add-mappings:false")
-				.run((context) -> assertThat(getResourceMappingLocations(context)).hasSize(1));
+				.run((context) -> assertThat(getResourceMappingLocations(context)).hasSize(0));
 	}
 
 	@Test
@@ -378,21 +378,6 @@ class WebMvcAutoConfigurationTests {
 						.containsOnly("myViewResolver"));
 	}
 
-	@Test
-	void faviconMapping() {
-		this.contextRunner.run((context) -> {
-			List<Resource> favIconResources = getResourceMappingLocations(context).get("/favicon.ico");
-			assertThat(favIconResources.stream().map(ClassPathResource.class::cast).map(ClassPathResource::getPath))
-					.containsExactly("META-INF/resources/", "resources/", "static/", "public/", "favicon.ico");
-		});
-	}
-
-	@Test
-	void faviconMappingDisabled() {
-		this.contextRunner.withPropertyValues("spring.mvc.favicon.enabled:false")
-				.run((context) -> assertThat(getResourceMappingLocations(context).get("/favicon.ico")).isNull());
-	}
-
 	@Test
 	void defaultAsyncRequestTimeout() {
 		this.contextRunner.run((context) -> assertThat(ReflectionTestUtils
@@ -660,9 +645,8 @@ class WebMvcAutoConfigurationTests {
 
 	private void assertCachePeriod(AssertableWebApplicationContext context) {
 		Map<String, Object> handlerMap = getHandlerMap(context.getBean("resourceHandlerMapping", HandlerMapping.class));
-		assertThat(handlerMap).hasSize(3);
+		assertThat(handlerMap).hasSize(2);
 		for (Entry<String, Object> entry : handlerMap.entrySet()) {
-			if (!entry.getKey().equals("/favicon.ico")) {
 			Object handler = entry.getValue();
 			if (handler instanceof ResourceHttpRequestHandler) {
 				assertThat(((ResourceHttpRequestHandler) handler).getCacheSeconds()).isEqualTo(5);
@@ -670,7 +654,6 @@ class WebMvcAutoConfigurationTests {
 			}
 		}
 	}
-	}
 
 	@Test
 	void cacheControl() {
@@ -784,7 +767,7 @@ class WebMvcAutoConfigurationTests {
 
 	private void assertCacheControl(AssertableWebApplicationContext context) {
 		Map<String, Object> handlerMap = getHandlerMap(context.getBean("resourceHandlerMapping", HandlerMapping.class));
-		assertThat(handlerMap).hasSize(3);
+		assertThat(handlerMap).hasSize(2);
 		for (Object handler : handlerMap.keySet()) {
 			if (handler instanceof ResourceHttpRequestHandler) {
 				assertThat(((ResourceHttpRequestHandler) handler).getCacheSeconds()).isEqualTo(-1);
@@ -795,8 +778,13 @@ class WebMvcAutoConfigurationTests {
 	}
 
 	protected Map<String, List<Resource>> getResourceMappingLocations(ApplicationContext context) {
+		Object bean = context.getBean("resourceHandlerMapping");
+		if (bean instanceof HandlerMapping) {
 			return getMappingLocations(context.getBean("resourceHandlerMapping", HandlerMapping.class));
 		}
+		assertThat(bean.toString()).isEqualTo("null");
+		return Collections.emptyMap();
+	}
 
 	protected List<ResourceResolver> getResourceResolvers(ApplicationContext context, String mapping) {
 		ResourceHttpRequestHandler resourceHandler = (ResourceHttpRequestHandler) context

spring-boot-project/spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -2508,9 +2508,9 @@ welcome page of the application.
 
 [[boot-features-spring-mvc-favicon]]
 ==== Custom Favicon
-Spring Boot looks for a `favicon.ico` in the configured static content locations and the
-root of the classpath (in that order). If such a file is present, it is automatically
-used as the favicon of the application.
+As with other static resources, Spring Boot looks for a `favicon.ico` in the configured
+static content locations. If such a file is present, it is automatically used as the
+favicon of the application.
 
 
 [[boot-features-spring-mvc-pathmatch]]