Support relaxed HealthMvcEndpoint status mappings

Update HealthMvcEndpoint so that relaxed names can be used as keys in
the `endpoints.health.mapping` property.

Fixes gh-2465

Author: philwebb

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

@@ -25,6 +25,7 @@
 import org.springframework.boot.actuate.endpoint.HealthEndpoint;
 import org.springframework.boot.actuate.health.Health;
 import org.springframework.boot.actuate.health.Status;
+import org.springframework.boot.bind.RelaxedNames;
 import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.context.EnvironmentAware;
 import org.springframework.core.env.Environment;
@@ -128,13 +129,27 @@ public Object invoke(Principal principal) {
 					"message", "This endpoint is disabled"), HttpStatus.NOT_FOUND);
 		}
 		Health health = getHealth(principal);
-		HttpStatus status = this.statusMapping.get(health.getStatus().getCode());
+		HttpStatus status = getStatus(health);
 		if (status != null) {
 			return new ResponseEntity<Health>(health, status);
 		}
 		return health;
 	}
 
+	private HttpStatus getStatus(Health health) {
+		String code = health.getStatus().getCode();
+		if (code != null) {
+			code = code.toLowerCase().replace("_", "-");
+			for (String candidate : RelaxedNames.forCamelCase(code)) {
+				HttpStatus status = this.statusMapping.get(candidate);
+				if (status != null) {
+					return status;
+				}
+			}
+		}
+		return null;
+	}
+
 	private Health getHealth(Principal principal) {
 		long accessTime = System.currentTimeMillis();
 		if (isCacheStale(accessTime)) {

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

@@ -91,8 +91,8 @@ public void down() {
 		assertEquals(HttpStatus.SERVICE_UNAVAILABLE, response.getStatusCode());
 	}
 
-	@SuppressWarnings("unchecked")
 	@Test
+	@SuppressWarnings("unchecked")
 	public void customMapping() {
 		given(this.endpoint.invoke()).willReturn(
 				new Health.Builder().status("OK").build());
@@ -105,6 +105,20 @@ public void customMapping() {
 		assertEquals(HttpStatus.INTERNAL_SERVER_ERROR, response.getStatusCode());
 	}
 
+	@Test
+	@SuppressWarnings("unchecked")
+	public void customMappingWithRelaxedName() {
+		given(this.endpoint.invoke()).willReturn(
+				new Health.Builder().outOfService().build());
+		this.mvc.setStatusMapping(Collections.singletonMap("out-of-service",
+				HttpStatus.INTERNAL_SERVER_ERROR));
+		Object result = this.mvc.invoke(null);
+		assertTrue(result instanceof ResponseEntity);
+		ResponseEntity<Health> response = (ResponseEntity<Health>) result;
+		assertTrue(response.getBody().getStatus().equals(Status.OUT_OF_SERVICE));
+		assertEquals(HttpStatus.INTERNAL_SERVER_ERROR, response.getStatusCode());
+	}
+
 	@Test
 	public void secure() {
 		given(this.endpoint.invoke()).willReturn(