Use lowercase default endpoint paths

Update `MappingWebEndpointPathMapper` to use the lowercase version of
the endpoint ID when no explicit path mapping has been set. An endpoint
with the ID 'myEndpoint' will now be mapped to the path 'myendpoint'.

See gh-14773

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/endpoint/web/MappingWebEndpointPathMapper.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.actuate.autoconfigure.endpoint.web;
 
+import java.util.HashMap;
 import java.util.Map;
 
 import org.springframework.boot.actuate.endpoint.EndpointId;
@@ -29,10 +30,12 @@ import org.springframework.boot.actuate.endpoint.web.PathMapper;
  */
 class MappingWebEndpointPathMapper implements PathMapper {
 
-	private final Map<String, String> pathMapping;
+	private final Map<EndpointId, String> pathMapping;
 
 	MappingWebEndpointPathMapper(Map<String, String> pathMapping) {
-		this.pathMapping = pathMapping;
+		this.pathMapping = new HashMap<>();
+		pathMapping.forEach((id, path) -> this.pathMapping
+				.put(EndpointId.fromPropertyValue(id), path));
 	}
 
 	@Override

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/endpoint/web/MappingWebEndpointPathMapperTests.java

@@ -45,4 +45,19 @@ public class MappingWebEndpointPathMapperTests {
 		assertThat(mapper.getRootPath(EndpointId.of("test"))).isEqualTo("custom");
 	}
 
+	@Test
+	public void mixedCaseDefaultConfiguration() {
+		MappingWebEndpointPathMapper mapper = new MappingWebEndpointPathMapper(
+				Collections.emptyMap());
+		assertThat(mapper.getRootPath(EndpointId.of("testEndpoint")))
+				.isEqualTo("testendpoint");
+	}
+
+	@Test
+	public void mixedCaseUserConfiguration() {
+		MappingWebEndpointPathMapper mapper = new MappingWebEndpointPathMapper(
+				Collections.singletonMap("test-endpoint", "custom"));
+		assertThat(mapper.getRootPath(EndpointId.of("testEndpoint"))).isEqualTo("custom");
+	}
+
 }