Register ServiceLevelObjectiveBoundary reflection hinds

Register hints for `ServiceLevelObjectiveBoundary` so that the `valueOf`
method can be used when binding in a native image.

Fixes gh-40480

Author: philwebb

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/ServiceLevelObjectiveBoundary.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -20,6 +20,10 @@
 
 import io.micrometer.core.instrument.Meter;
 
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.RuntimeHintsRegistrar;
+
 /**
  * A boundary for a service-level objective (SLO) for use when configuring Micrometer. Can
  * be specified as either a {@link Double} (applicable to timers and distribution
@@ -67,4 +71,13 @@ public static ServiceLevelObjectiveBoundary valueOf(String value) {
 		return new ServiceLevelObjectiveBoundary(MeterValue.valueOf(value));
 	}
 
+	static class ServiceLevelObjectiveBoundaryHints implements RuntimeHintsRegistrar {
+
+		@Override
+		public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+			hints.reflection().registerType(ServiceLevelObjectiveBoundary.class, MemberCategory.INVOKE_PUBLIC_METHODS);
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/resources/META-INF/spring/aot.factories

@@ -0,0 +1,2 @@
+org.springframework.aot.hint.RuntimeHintsRegistrar=\
+org.springframework.boot.actuate.autoconfigure.metrics.ServiceLevelObjectiveBoundary.ServiceLevelObjectiveBoundaryHints

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/ServiceLevelObjectiveBoundaryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -21,6 +21,10 @@
 import io.micrometer.core.instrument.Meter.Type;
 import org.junit.jupiter.api.Test;
 
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.predicate.RuntimeHintsPredicates;
+import org.springframework.util.ReflectionUtils;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
@@ -73,4 +77,16 @@ void getValueForDistributionSummaryWhenFromDurationShouldReturnNull() {
 		assertThat(slo.getValue(Type.DISTRIBUTION_SUMMARY)).isNull();
 	}
 
+	@Test
+	void shouldRegisterRuntimeHints() {
+		RuntimeHints runtimeHints = new RuntimeHints();
+		new ServiceLevelObjectiveBoundary.ServiceLevelObjectiveBoundaryHints().registerHints(runtimeHints,
+				getClass().getClassLoader());
+		ReflectionUtils.doWithLocalMethods(ServiceLevelObjectiveBoundary.class, (method) -> {
+			if ("valueOf".equals(method.getName())) {
+				assertThat(RuntimeHintsPredicates.reflection().onMethod(method)).accepts(runtimeHints);
+			}
+		});
+	}
+
 }