Make CompositeHealth.getDetails() public

Change `CompositeHealth.getDetails()` to public so that it serializes
correctly when `MapperFeature.CAN_OVERRIDE_ACCESS_MODIFIERS` is
disabled.

Fixes gh-26797

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/CompositeHealth.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -66,7 +66,7 @@ public class CompositeHealth extends HealthComponent {
 
 	@JsonInclude(Include.NON_EMPTY)
 	@JsonProperty
-	Map<String, HealthComponent> getDetails() {
+	public Map<String, HealthComponent> getDetails() {
 		return this.details;
 	}
 

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/health/CompositeHealthTests.java

 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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 +20,7 @@ import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import com.fasterxml.jackson.databind.MapperFeature;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.jupiter.api.Test;
 
@@ -80,4 +81,17 @@ class CompositeHealthTests {
 				+ "\"db2\":{\"status\":\"DOWN\",\"details\":{\"a\":\"b\"}}}}");
 	}
 
+	@Test // gh-26797
+	void serializeV2WithJacksonAndDisabledCanOverrideAccessModifiersReturnsValidJson() throws Exception {
+		Map<String, HealthComponent> components = new LinkedHashMap<>();
+		components.put("db1", Health.up().build());
+		components.put("db2", Health.down().withDetail("a", "b").build());
+		CompositeHealth health = new CompositeHealth(ApiVersion.V2, Status.UP, components);
+		ObjectMapper mapper = new ObjectMapper();
+		mapper.disable(MapperFeature.CAN_OVERRIDE_ACCESS_MODIFIERS);
+		String json = mapper.writeValueAsString(health);
+		assertThat(json).isEqualTo("{\"status\":\"UP\",\"details\":{\"db1\":{\"status\":\"UP\"},"
+				+ "\"db2\":{\"status\":\"DOWN\",\"details\":{\"a\":\"b\"}}}}");
+	}
+
 }