Fix containsDescendantOf for random sources

Fix the `containsDescendantOf` logic for random property sources to
ensure that ancestors are correctly matched.

Closes gh-21654

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SpringConfigurationPropertySource.java

@@ -190,7 +190,7 @@ class SpringConfigurationPropertySource implements ConfigurationPropertySource {
 	}
 
 	private static ConfigurationPropertyState containsDescendantOfForRandom(ConfigurationPropertyName name) {
-		if (name.isAncestorOf(RANDOM) || name.equals(RANDOM)) {
+		if (RANDOM.isAncestorOf(name) || name.equals(RANDOM)) {
 			return ConfigurationPropertyState.PRESENT;
 		}
 		return ConfigurationPropertyState.ABSENT;

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/source/SpringConfigurationPropertySourceTests.java

@@ -21,6 +21,7 @@ import java.util.Map;
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.boot.env.RandomValuePropertySource;
 import org.springframework.boot.origin.Origin;
 import org.springframework.boot.origin.OriginLookup;
 import org.springframework.core.env.MapPropertySource;
@@ -148,6 +149,30 @@ class SpringConfigurationPropertySourceTests {
 				.isInstanceOf(IterableConfigurationPropertySource.class);
 	}
 
+	@Test
+	void containsDescendantOfWhenRandomSourceAndRandomPropertyReturnsPresent() {
+		SpringConfigurationPropertySource source = SpringConfigurationPropertySource
+				.from(new RandomValuePropertySource());
+		assertThat(source.containsDescendantOf(ConfigurationPropertyName.of("random")))
+				.isEqualTo(ConfigurationPropertyState.PRESENT);
+	}
+
+	@Test
+	void containsDescendantOfWhenRandomSourceAndRandomPrefixedPropertyReturnsPresent() {
+		SpringConfigurationPropertySource source = SpringConfigurationPropertySource
+				.from(new RandomValuePropertySource());
+		assertThat(source.containsDescendantOf(ConfigurationPropertyName.of("random.something")))
+				.isEqualTo(ConfigurationPropertyState.PRESENT);
+	}
+
+	@Test
+	void containsDescendantOfWhenRandomSourceAndNonRandomPropertyReturnsAbsent() {
+		SpringConfigurationPropertySource source = SpringConfigurationPropertySource
+				.from(new RandomValuePropertySource());
+		assertThat(source.containsDescendantOf(ConfigurationPropertyName.of("abandon.something")))
+				.isEqualTo(ConfigurationPropertyState.ABSENT);
+	}
+
 	/**
 	 * Test {@link PropertySource} that's also an {@link OriginLookup}.
 	 *