Prioritise static resource locations over classpath for favicon.ico

Closes gh-17922

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

@@ -336,10 +336,18 @@ public class WebMvcAutoConfiguration {
 		@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("classpath:favicon.ico");
+					registry.addResourceHandler("favicon.ico")
+							.addResourceLocations(this.resourceProperties.getStaticLocations())
+							.addResourceLocations("classpath:favicon.ico");
 				}
 			}
 

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

@@ -380,8 +380,11 @@ class WebMvcAutoConfigurationTests {
 
 	@Test
 	void faviconMapping() {
-		this.contextRunner
-				.run((context) -> assertThat(getResourceMappingLocations(context).get("/favicon.ico")).hasSize(1));
+		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