Cleanup URLs before using them for metrics

Update `WebMvcTags` to cleanup URLs by removing any double
slashes and any trailing slash.

Fixes gh-11808

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcTags.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -84,6 +84,7 @@ public final class WebMvcTags {
 		if (!StringUtils.hasText(uri)) {
 			uri = "/";
 		}
+		uri = uri.replaceAll("//+", "/").replaceAll("/$", "");
 		return Tag.of("uri", uri.isEmpty() ? "root" : uri);
 	}
 

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/servlet/WebMvcTagsTests.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -22,6 +22,7 @@ import org.junit.Test;
 import org.springframework.boot.actuate.metrics.web.servlet.WebMvcTags;
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.web.servlet.HandlerMapping;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -36,6 +37,13 @@ public class WebMvcTagsTests {
 
 	private final MockHttpServletResponse response = new MockHttpServletResponse();
 
+	@Test
+	public void uriTrailingSlashesAreSuppressed() {
+		this.request.setAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE,
+				"//foo/");
+		assertThat(WebMvcTags.uri(this.request, null).getValue()).isEqualTo("/foo");
+	}
+
 	@Test
 	public void uriTagValueIsRedirectionWhenResponseStatusIs3xx() {
 		this.response.setStatus(301);
@@ -54,7 +62,7 @@ public class WebMvcTagsTests {
 	public void uriTagToleratesCustomResponseStatus() {
 		this.response.setStatus(601);
 		Tag tag = WebMvcTags.uri(this.request, this.response);
-		assertThat(tag.getValue()).isEqualTo("/");
+		assertThat(tag.getValue()).isEqualTo("root");
 	}
 
 }