Remove HalJsonMvcEndpoint’s redirect and add links to both paths instead

Previously, HalJsonMvcEndpoint used a redirect to go from path/ to path.
When the actuator’s configured to use a custom context path this
redirect was leading to an infinite redirect loop.

This commit removes the redirect in favour of updating the controller
advice to apply the links to requests for path and path/.

Closes gh-4853

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/EndpointWebMvcHypermediaManagementContextConfiguration.java

 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -196,8 +196,12 @@ public class EndpointWebMvcHypermediaManagementContextConfiguration {
 		}
 
 		private boolean isActuatorEndpointPath(String path) {
-			return this.halJsonMvcEndpoint != null && (this.management.getContextPath()
-					+ this.halJsonMvcEndpoint.getPath()).equals(path);
+			if (this.halJsonMvcEndpoint != null) {
+				String toMatch = this.management.getContextPath()
+						+ this.halJsonMvcEndpoint.getPath();
+				return toMatch.equals(path) || (toMatch + "/").equals(path);
+			}
+			return false;
 		}
 
 	}

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/HalJsonMvcEndpoint.java

 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -87,11 +87,6 @@ public class HalJsonMvcEndpoint extends WebMvcConfigurerAdapter
 		return new ResourceSupport();
 	}
 
-	@RequestMapping(path = "/", produces = MediaType.APPLICATION_JSON_VALUE)
-	public String forward() {
-		return "redirect:" + this.managementServletContext.getContextPath() + this.path;
-	}
-
 	public void setPath(String path) {
 		this.path = path;
 	}

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/HalBrowserMvcEndpointManagementContextPathIntegrationTests.java

 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -39,7 +39,6 @@ import org.springframework.web.context.WebApplicationContext;
 import static org.springframework.hateoas.mvc.ControllerLinkBuilder.linkTo;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.forwardedUrl;
-import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.header;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
@@ -77,10 +76,9 @@ public class HalBrowserMvcEndpointManagementContextPathIntegrationTests {
 	}
 
 	@Test
-	public void redirectJson() throws Exception {
+	public void actuatorHomeWithTrailingSlashJson() throws Exception {
 		this.mockMvc.perform(get("/admin/").accept(MediaType.APPLICATION_JSON))
-				.andExpect(status().isFound())
-				.andExpect(header().string("location", "/admin"));
+				.andExpect(status().isOk()).andExpect(jsonPath("$._links").exists());
 	}
 
 	@Test

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/HalBrowserMvcEndpointServerContextPathIntegrationTests.java

 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -97,6 +97,18 @@ public class HalBrowserMvcEndpointServerContextPathIntegrationTests {
 				entity.getBody().contains("\"_links\":"));
 	}
 
+	@Test
+	public void actuatorLinksWithTrailingSlash() throws Exception {
+		HttpHeaders headers = new HttpHeaders();
+		headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
+		ResponseEntity<String> entity = new TestRestTemplate().exchange(
+				"http://localhost:" + this.port + "/spring/actuator/", HttpMethod.GET,
+				new HttpEntity<Void>(null, headers), String.class);
+		assertEquals(HttpStatus.OK, entity.getStatusCode());
+		assertTrue("Wrong body: " + entity.getBody(),
+				entity.getBody().contains("\"_links\":"));
+	}
+
 	@MinimalActuatorHypermediaApplication
 	@RestController
 	public static class SpringBootHypermediaApplication {

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/HalBrowserMvcEndpointServerPortIntegrationTests.java

 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -75,6 +75,20 @@ public class HalBrowserMvcEndpointServerPortIntegrationTests {
 				entity.getBody().contains(":" + this.port));
 	}
 
+	@Test
+	public void linksWithTrailingSlash() throws Exception {
+		HttpHeaders headers = new HttpHeaders();
+		headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
+		ResponseEntity<String> entity = new TestRestTemplate().exchange(
+				"http://localhost:" + this.port + "/actuator/", HttpMethod.GET,
+				new HttpEntity<Void>(null, headers), String.class);
+		assertEquals(HttpStatus.OK, entity.getStatusCode());
+		assertTrue("Wrong body: " + entity.getBody(),
+				entity.getBody().contains("\"_links\":"));
+		assertTrue("Wrong body: " + entity.getBody(),
+				entity.getBody().contains(":" + this.port));
+	}
+
 	@Test
 	public void browser() throws Exception {
 		HttpHeaders headers = new HttpHeaders();

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/HalBrowserMvcEndpointVanillaIntegrationTests.java

 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -78,6 +78,13 @@ public class HalBrowserMvcEndpointVanillaIntegrationTests {
 				.andExpect(header().doesNotExist("cache-control"));
 	}
 
+	@Test
+	public void linksWithTrailingSlash() throws Exception {
+		this.mockMvc.perform(get("/actuator/").accept(MediaType.APPLICATION_JSON))
+				.andExpect(status().isOk()).andExpect(jsonPath("$._links").exists())
+				.andExpect(header().doesNotExist("cache-control"));
+	}
+
 	@Test
 	public void browser() throws Exception {
 		MvcResult response = this.mockMvc