Merge pull request #14967 from chang-chao

* pr/14967:
  Polish "Consider aliases when checking descendants"
  Consider aliases when checking descendants

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

@@ -65,6 +65,15 @@ class AliasedConfigurationPropertySource implements ConfigurationPropertySource
 				return aliasResult;
 			}
 		}
+		for (ConfigurationPropertyName from : getAliases()) {
+			for (ConfigurationPropertyName alias : getAliases().getAliases(from)) {
+				if (name.isAncestorOf(alias)) {
+					if (this.source.getConfigurationProperty(from) != null) {
+						return ConfigurationPropertyState.PRESENT;
+					}
+				}
+			}
+		}
 		return ConfigurationPropertyState.ABSENT;
 	}
 

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

@@ -18,6 +18,7 @@ package org.springframework.boot.context.properties.source;
 
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 
@@ -33,7 +34,8 @@ import org.springframework.util.MultiValueMap;
  * @since 2.0.0
  * @see ConfigurationPropertySource#withAliases(ConfigurationPropertyNameAliases)
  */
-public final class ConfigurationPropertyNameAliases {
+public final class ConfigurationPropertyNameAliases
+		implements Iterable<ConfigurationPropertyName> {
 
 	private final MultiValueMap<ConfigurationPropertyName, ConfigurationPropertyName> aliases = new LinkedMultiValueMap<>();
 
@@ -74,4 +76,9 @@ public final class ConfigurationPropertyNameAliases {
 				.findFirst().orElse(null);
 	}
 
+	@Override
+	public Iterator<ConfigurationPropertyName> iterator() {
+		return this.aliases.keySet().iterator();
+	}
+
 }

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

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.context.properties.source;
 
+import java.util.Collections;
+
 import org.junit.Test;
 import org.mockito.Answers;
 
@@ -111,6 +113,16 @@ public class AliasedConfigurationPropertySourceTests {
 				.isEqualTo(ConfigurationPropertyState.PRESENT);
 	}
 
+	@Test
+	public void containsDescendantOfWhenPresentInAliasShouldReturnPresent() {
+		ConfigurationPropertySource source = new MapConfigurationPropertySource(
+				Collections.singletonMap("foo.bar", "foobar"));
+		ConfigurationPropertySource aliased = source
+				.withAliases(new ConfigurationPropertyNameAliases("foo.bar", "baz.foo"));
+		assertThat(aliased.containsDescendantOf(ConfigurationPropertyName.of("baz")))
+				.isEqualTo(ConfigurationPropertyState.PRESENT);
+	}
+
 	private Object getValue(ConfigurationPropertySource source, String name) {
 		ConfigurationProperty property = source
 				.getConfigurationProperty(ConfigurationPropertyName.of(name));