Use a HandlerInterceptor for timing long tasks

Closes gh-15204

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/web/servlet/WebMvcMetricsAutoConfigurationTests.java

@@ -33,6 +33,7 @@ import org.junit.Test;
 import org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.metrics.web.TestController;
 import org.springframework.boot.actuate.metrics.web.servlet.DefaultWebMvcTagsProvider;
+import org.springframework.boot.actuate.metrics.web.servlet.LongTaskTimingHandlerInterceptor;
 import org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter;
 import org.springframework.boot.actuate.metrics.web.servlet.WebMvcTagsProvider;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
@@ -47,6 +48,7 @@ import org.springframework.core.Ordered;
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
 import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
@@ -140,6 +142,22 @@ public class WebMvcMetricsAutoConfigurationTests {
 				});
 	}
 
+	@Test
+	@SuppressWarnings("rawtypes")
+	public void longTaskTimingInterceptorIsRegistered() {
+		this.contextRunner
+				.withUserConfiguration(TestController.class,
+						MeterRegistryConfiguration.class)
+				.withConfiguration(AutoConfigurations.of(MetricsAutoConfiguration.class,
+						WebMvcAutoConfiguration.class))
+				.run((context) -> {
+					assertThat(context.getBean(RequestMappingHandlerMapping.class))
+							.extracting("interceptors").element(0).asList()
+							.extracting((item) -> (Class) item.getClass())
+							.contains(LongTaskTimingHandlerInterceptor.class);
+				});
+	}
+
 	private MeterRegistry getInitializedMeterRegistry(
 			AssertableWebApplicationContext context) throws Exception {
 		assertThat(context).hasSingleBean(FilterRegistrationBean.class);