Polish "Look in correct context when finding Liquibase beans"

See gh-22681

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/liquibase/LiquibaseEndpoint.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/liquibase/LiquibaseEndpointTests.java

@@ -62,6 +62,17 @@ class LiquibaseEndpointTests {
 		});
 	}
 
+	@Test
+	void liquibaseReportIsReturnedForContextHierarchy() {
+		this.contextRunner.withUserConfiguration().run((parent) -> {
+			this.contextRunner.withUserConfiguration(Config.class).withParent(parent).run((context) -> {
+				Map<String, LiquibaseBean> liquibaseBeans = context.getBean(LiquibaseEndpoint.class).liquibaseBeans()
+						.getContexts().get(parent.getId()).getLiquibaseBeans();
+				assertThat(liquibaseBeans.get("liquibase").getChangeSets()).hasSize(1);
+			});
+		});
+	}
+
 	@Test
 	void invokeWithCustomSchema() {
 		this.contextRunner.withUserConfiguration(Config.class)