Add 'contains descendant of' support

Update `ConfigurationPropertySource` with a `containsDescendantOf`
method that can be used to tell if a source contains any descendants
of the given name.

The result is Optional so that sources that cannot determine a result
may return `empty()`.

The existing `IterableConfigurationPropertiesSource` has a default
implementation that works by iterating the contained values. Most other
sources return `empty()` with the exception of the adapted
`RandomProperySource` with will return true for `random.*` names.

See gh-9023

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

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.context.properties.source;
 
+import java.util.Optional;
+
 import org.springframework.util.Assert;
 
 /**
@@ -50,6 +52,17 @@ class AliasedConfigurationPropertySource implements ConfigurationPropertySource
 		return result;
 	}
 
+	@Override
+	public Optional<Boolean> containsDescendantOf(ConfigurationPropertyName name) {
+		Assert.notNull(name, "Name must not be null");
+		Optional<Boolean> result = this.source.containsDescendantOf(name);
+		for (ConfigurationPropertyName alias : getAliases().getAliases(name)) {
+			Optional<Boolean> aliasResult = this.source.containsDescendantOf(alias);
+			result = result.flatMap((r) -> aliasResult.flatMap(a -> Optional.of(r || a)));
+		}
+		return result;
+	}
+
 	protected ConfigurationPropertySource getSource() {
 		return this.source;
 	}

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

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.context.properties.source;
 
+import java.util.Optional;
 import java.util.function.Predicate;
 
 import org.springframework.boot.origin.OriginTrackedValue;
@@ -40,6 +41,27 @@ public interface ConfigurationPropertySource {
 	 */
 	ConfigurationProperty getConfigurationProperty(ConfigurationPropertyName name);
 
+	/**
+	 * Optionally returns if the source contains any descendants of the specified name.
+	 * <ul>
+	 * <li>A result of {@code true} means that there is at least on property in the source
+	 * with a name that's an
+	 * {@link ConfigurationPropertyName#isAncestorOf(ConfigurationPropertyName) ancestor}
+	 * of {@code name}.</li>
+	 * <li>A result of {@code false} means that that there are no properties in the source
+	 * with a name that's an
+	 * {@link ConfigurationPropertyName#isAncestorOf(ConfigurationPropertyName) ancestor}
+	 * of {@code name}.</li>
+	 * <li>A result of {@code empty} means it is not possible to determine up determine if
+	 * there's a property in the source with a name that's an
+	 * {@link ConfigurationPropertyName#isAncestorOf(ConfigurationPropertyName) ancestor}
+	 * of {@code name}.
+	 * </ul>
+	 * @param name the name to check
+	 * @return an optional boolean determining if a descendant is contained in the source
+	 */
+	Optional<Boolean> containsDescendantOf(ConfigurationPropertyName name);
+
 	/**
 	 * Return a filtered variant of this source, containing only names that match the
 	 * given {@link Predicate}.

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

@@ -18,15 +18,19 @@ package org.springframework.boot.context.properties.source;
 
 import java.util.Iterator;
 import java.util.Map;
+import java.util.Optional;
 import java.util.WeakHashMap;
+import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
 
+import org.springframework.boot.env.RandomValuePropertySource;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.EnumerablePropertySource;
 import org.springframework.core.env.MutablePropertySources;
 import org.springframework.core.env.PropertySource;
+import org.springframework.core.env.PropertySource.StubPropertySource;
 import org.springframework.core.env.PropertySources;
 import org.springframework.core.env.PropertySourcesPropertyResolver;
 import org.springframework.core.env.SystemEnvironmentPropertySource;
@@ -45,6 +49,9 @@ import org.springframework.util.Assert;
 public class ConfigurationPropertySources
 		implements Iterable<ConfigurationPropertySource> {
 
+	private static final ConfigurationPropertyName RANDOM = ConfigurationPropertyName
+			.of("random");
+
 	/**
 	 * The name of the {@link PropertySource} {@link #adapt adapter}.
 	 */
@@ -71,7 +78,8 @@ public class ConfigurationPropertySources
 	}
 
 	private Stream<PropertySource<?>> streamPropertySources(PropertySources sources) {
-		return StreamSupport.stream(sources.spliterator(), false).flatMap(this::flatten);
+		return StreamSupport.stream(sources.spliterator(), false).flatMap(this::flatten)
+				.filter(this::notStubSource);
 	}
 
 	private Stream<PropertySource<?>> flatten(PropertySource<?> source) {
@@ -82,6 +90,10 @@ public class ConfigurationPropertySources
 		return Stream.of(source);
 	}
 
+	private boolean notStubSource(PropertySource<?> source) {
+		return !(source instanceof StubPropertySource);
+	}
+
 	private ConfigurationPropertySource adapt(PropertySource<?> source) {
 		return this.adapters.computeIfAbsent(source, this::createAdapter);
 	}
@@ -92,7 +104,8 @@ public class ConfigurationPropertySources
 			return new PropertySourceIterableConfigurationPropertySource(
 					(EnumerablePropertySource<?>) source, mapper);
 		}
-		return new PropertySourceConfigurationPropertySource(source, mapper);
+		return new PropertySourceConfigurationPropertySource(source, mapper,
+				getContainsDescendantOfMethod(source));
 	}
 
 	private PropertyMapper getPropertyMapper(PropertySource<?> source) {
@@ -124,6 +137,15 @@ public class ConfigurationPropertySources
 		return source;
 	}
 
+	private Function<ConfigurationPropertyName, Optional<Boolean>> getContainsDescendantOfMethod(
+			PropertySource<?> source) {
+		if (source instanceof RandomValuePropertySource) {
+			return (name) -> Optional
+					.of(name.isAncestorOf(RANDOM) || name.equals(RANDOM));
+		}
+		return null;
+	}
+
 	/**
 	 * Attach a {@link ConfigurationPropertySources} instance to the specified
 	 * {@link ConfigurableEnvironment} so that classic

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

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.context.properties.source;
 
+import java.util.Optional;
 import java.util.function.Predicate;
 
 import org.springframework.util.Assert;
@@ -47,6 +48,13 @@ class FilteredConfigurationPropertiesSource implements ConfigurationPropertySour
 		return (filtered ? getSource().getConfigurationProperty(name) : null);
 	}
 
+	@Override
+	public Optional<Boolean> containsDescendantOf(ConfigurationPropertyName name) {
+		// We can't be sure a contained descendant won't be filtered
+		return this.source.containsDescendantOf(name)
+				.flatMap((result) -> result ? Optional.empty() : Optional.of(result));
+	}
+
 	protected ConfigurationPropertySource getSource() {
 		return this.source;
 	}

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

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.context.properties.source;
 
+import java.util.Optional;
 import java.util.function.Predicate;
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
@@ -46,4 +47,9 @@ class FilteredIterableConfigurationPropertiesSource
 		return (IterableConfigurationPropertySource) super.getSource();
 	}
 
+	@Override
+	public Optional<Boolean> containsDescendantOf(ConfigurationPropertyName name) {
+		return Optional.of(stream().filter(name::isAncestorOf).findFirst().isPresent());
+	}
+
 }

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

@@ -17,6 +17,7 @@
 package org.springframework.boot.context.properties.source;
 
 import java.util.Iterator;
+import java.util.Optional;
 import java.util.function.Predicate;
 import java.util.stream.Stream;
 
@@ -60,6 +61,11 @@ public interface IterableConfigurationPropertySource
 	 */
 	Stream<ConfigurationPropertyName> stream();
 
+	@Override
+	default Optional<Boolean> containsDescendantOf(ConfigurationPropertyName name) {
+		return Optional.of(stream().filter(name::isAncestorOf).findFirst().isPresent());
+	}
+
 	@Override
 	default IterableConfigurationPropertySource filter(
 			Predicate<ConfigurationPropertyName> filter) {

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

@@ -19,6 +19,8 @@ package org.springframework.boot.context.properties.source;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
+import java.util.function.Function;
 
 import org.springframework.boot.origin.Origin;
 import org.springframework.boot.origin.PropertySourceOrigin;
@@ -54,17 +56,24 @@ class PropertySourceConfigurationPropertySource implements ConfigurationProperty
 
 	private final PropertyMapper mapper;
 
+	private final Function<ConfigurationPropertyName, Optional<Boolean>> containsDescendantOfMethod;
+
 	/**
 	 * Create a new {@link PropertySourceConfigurationPropertySource} implementation.
 	 * @param propertySource the source property source
 	 * @param mapper the property mapper
+	 * @param containsDescendantOfMethod function used to implement
+	 * {@link #containsDescendantOf(ConfigurationPropertyName)} (may be {@code null})
 	 */
 	PropertySourceConfigurationPropertySource(PropertySource<?> propertySource,
-			PropertyMapper mapper) {
+			PropertyMapper mapper,
+			Function<ConfigurationPropertyName, Optional<Boolean>> containsDescendantOfMethod) {
 		Assert.notNull(propertySource, "PropertySource must not be null");
 		Assert.notNull(mapper, "Mapper must not be null");
 		this.propertySource = propertySource;
 		this.mapper = new ExceptionSwallowingPropertyMapper(mapper);
+		this.containsDescendantOfMethod = (containsDescendantOfMethod != null ? containsDescendantOfMethod
+				: (n) -> Optional.empty());
 	}
 
 	@Override
@@ -74,6 +83,11 @@ class PropertySourceConfigurationPropertySource implements ConfigurationProperty
 		return find(mappings, name);
 	}
 
+	@Override
+	public Optional<Boolean> containsDescendantOf(ConfigurationPropertyName name) {
+		return this.containsDescendantOfMethod.apply(name);
+	}
+
 	protected final ConfigurationProperty find(List<PropertyMapping> mappings,
 			ConfigurationPropertyName name) {
 		return mappings.stream().filter((m) -> m.isApplicable(name)).map(this::find)
@@ -101,6 +115,11 @@ class PropertySourceConfigurationPropertySource implements ConfigurationProperty
 		return this.mapper;
 	}
 
+	@Override
+	public String toString() {
+		return this.propertySource.toString();
+	}
+
 	/**
 	 * {@link PropertyMapper} that swallows exceptions when the mapping fails.
 	 */

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

@@ -20,6 +20,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Stream;
 
 import org.springframework.core.env.EnumerablePropertySource;
@@ -45,7 +46,7 @@ class PropertySourceIterableConfigurationPropertySource
 
 	PropertySourceIterableConfigurationPropertySource(
 			EnumerablePropertySource<?> propertySource, PropertyMapper mapper) {
-		super(propertySource, mapper);
+		super(propertySource, mapper, null);
 		assertEnumerablePropertySource(propertySource);
 	}
 
@@ -87,6 +88,11 @@ class PropertySourceIterableConfigurationPropertySource
 		return getConfigurationPropertyNames().iterator();
 	}
 
+	@Override
+	public Optional<Boolean> containsDescendantOf(ConfigurationPropertyName name) {
+		return Optional.of(stream().filter(name::isAncestorOf).findFirst().isPresent());
+	}
+
 	private List<ConfigurationPropertyName> getConfigurationPropertyNames() {
 		Cache cache = getCache();
 		List<ConfigurationPropertyName> names = (cache != null ? cache.getNames() : null);

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

@@ -16,9 +16,15 @@
 
 package org.springframework.boot.context.properties.source;
 
+import java.util.Optional;
+
 import org.junit.Test;
+import org.mockito.Answers;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.withSettings;
 
 /**
  * Tests for {@link AliasedConfigurationPropertySource}.
@@ -50,6 +56,59 @@ public class AliasedConfigurationPropertySourceTests {
 		assertThat(getValue(aliased, "foo.baz")).isEqualTo("biff");
 	}
 
+	@Test
+	public void containsDescendantOfWhenSourceReturnsEmptyShouldReturnEmpty()
+			throws Exception {
+		ConfigurationPropertyName name = ConfigurationPropertyName.of("foo");
+		ConfigurationPropertySource source = mock(ConfigurationPropertySource.class,
+				withSettings().defaultAnswer(Answers.CALLS_REAL_METHODS));
+		given(source.containsDescendantOf(name)).willReturn(Optional.empty());
+		ConfigurationPropertySource aliased = source
+				.withAliases(new ConfigurationPropertyNameAliases("foo.bar", "foo.bar1"));
+		assertThat(aliased.containsDescendantOf(name)).isEmpty();
+	}
+
+	@Test
+	public void containsDescendantOfWhenAliasReturnsEmptyShouldReturnEmpty()
+			throws Exception {
+		ConfigurationPropertyName name = ConfigurationPropertyName.of("foo");
+		ConfigurationPropertySource source = mock(ConfigurationPropertySource.class,
+				withSettings().defaultAnswer(Answers.CALLS_REAL_METHODS));
+		given(source.containsDescendantOf(name)).willReturn(Optional.of(true));
+		given(source.containsDescendantOf(ConfigurationPropertyName.of("bar")))
+				.willReturn(Optional.empty());
+		ConfigurationPropertySource aliased = source
+				.withAliases(new ConfigurationPropertyNameAliases("foo", "bar"));
+		assertThat(aliased.containsDescendantOf(name)).isEmpty();
+	}
+
+	@Test
+	public void containsDescendantOfWhenAllAreFalseShouldReturnFalse() throws Exception {
+		ConfigurationPropertyName name = ConfigurationPropertyName.of("foo");
+		ConfigurationPropertySource source = mock(ConfigurationPropertySource.class,
+				withSettings().defaultAnswer(Answers.CALLS_REAL_METHODS));
+		given(source.containsDescendantOf(name)).willReturn(Optional.of(false));
+		given(source.containsDescendantOf(ConfigurationPropertyName.of("bar")))
+				.willReturn(Optional.of(false));
+		ConfigurationPropertySource aliased = source
+				.withAliases(new ConfigurationPropertyNameAliases("foo", "bar"));
+		assertThat(aliased.containsDescendantOf(name)).contains(false);
+
+	}
+
+	@Test
+	public void containsDescendantOfWhenAnyIsTrueShouldReturnTrue() throws Exception {
+		ConfigurationPropertyName name = ConfigurationPropertyName.of("foo");
+		ConfigurationPropertySource source = mock(ConfigurationPropertySource.class,
+				withSettings().defaultAnswer(Answers.CALLS_REAL_METHODS));
+		given(source.containsDescendantOf(name)).willReturn(Optional.of(false));
+		given(source.containsDescendantOf(ConfigurationPropertyName.of("bar")))
+				.willReturn(Optional.of(true));
+		ConfigurationPropertySource aliased = source
+				.withAliases(new ConfigurationPropertyNameAliases("foo", "bar"));
+		assertThat(aliased.containsDescendantOf(name)).contains(true);
+	}
+
 	private Object getValue(ConfigurationPropertySource source, String name) {
 		ConfigurationProperty property = source
 				.getConfigurationProperty(ConfigurationPropertyName.of(name));

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

@@ -17,12 +17,17 @@
 package org.springframework.boot.context.properties.source;
 
 import java.util.Objects;
+import java.util.Optional;
 
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
+import org.mockito.Answers;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.withSettings;
 
 /**
  * Test for {@link FilteredIterableConfigurationPropertiesSource}.
@@ -61,7 +66,39 @@ public class FilteredConfigurationPropertiesSourceTests {
 		assertThat(source.getConfigurationProperty(bracketName).getValue())
 				.isEqualTo("2");
 		assertThat(filtered.getConfigurationProperty(bracketName)).isNull();
+	}
 
+	@Test
+	public void containsDescendantOfWhenSourceReturnsEmptyShouldReturnEmpty()
+			throws Exception {
+		ConfigurationPropertyName name = ConfigurationPropertyName.of("foo");
+		ConfigurationPropertySource source = mock(ConfigurationPropertySource.class,
+				withSettings().defaultAnswer(Answers.CALLS_REAL_METHODS));
+		given(source.containsDescendantOf(name)).willReturn(Optional.empty());
+		ConfigurationPropertySource filtered = source.filter((n) -> true);
+		assertThat(filtered.containsDescendantOf(name)).isEmpty();
+	}
+
+	@Test
+	public void containsDescendantOfWhenSourceReturnsFalseShouldReturnFalse()
+			throws Exception {
+		ConfigurationPropertyName name = ConfigurationPropertyName.of("foo");
+		ConfigurationPropertySource source = mock(ConfigurationPropertySource.class,
+				withSettings().defaultAnswer(Answers.CALLS_REAL_METHODS));
+		given(source.containsDescendantOf(name)).willReturn(Optional.of(false));
+		ConfigurationPropertySource filtered = source.filter((n) -> true);
+		assertThat(filtered.containsDescendantOf(name)).contains(false);
+	}
+
+	@Test
+	public void containsDescendantOfWhenSourceReturnsTrueShouldReturnEmpty()
+			throws Exception {
+		ConfigurationPropertyName name = ConfigurationPropertyName.of("foo");
+		ConfigurationPropertySource source = mock(ConfigurationPropertySource.class,
+				withSettings().defaultAnswer(Answers.CALLS_REAL_METHODS));
+		given(source.containsDescendantOf(name)).willReturn(Optional.of(true));
+		ConfigurationPropertySource filtered = source.filter((n) -> true);
+		assertThat(filtered.containsDescendantOf(name)).isEmpty();
 	}
 
 	protected final ConfigurationPropertySource createTestSource() {

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

@@ -43,6 +43,19 @@ public class FilteredIterableConfigurationPropertiesSourceTests
 		return source;
 	}
 
+	@Test
+	public void containsDescendantOfShouldUseContents() throws Exception {
+		MockConfigurationPropertySource source = new MockConfigurationPropertySource();
+		source.put("foo.bar.baz", "1");
+		source.put("foo.bar[0]", "1");
+		source.put("faf.bar[0]", "1");
+		IterableConfigurationPropertySource filtered = source.filter(this::noBrackets);
+		assertThat(filtered.containsDescendantOf(ConfigurationPropertyName.of("foo")))
+				.contains(true);
+		assertThat(filtered.containsDescendantOf(ConfigurationPropertyName.of("faf")))
+				.contains(false);
+	}
+
 	private boolean noBrackets(ConfigurationPropertyName name) {
 		return name.toString().indexOf("[") == -1;
 	}

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

@@ -19,6 +19,7 @@ package org.springframework.boot.context.properties.source;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.Optional;
 import java.util.stream.Stream;
 
 import org.springframework.boot.origin.MockOrigin;
@@ -97,6 +98,11 @@ public class MockConfigurationPropertySource
 			return MockConfigurationPropertySource.this.getConfigurationProperty(name);
 		}
 
+		@Override
+		public Optional<Boolean> containsDescendantOf(ConfigurationPropertyName name) {
+			return Optional.empty();
+		}
+
 	}
 
 }

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

@@ -46,14 +46,16 @@ public class PropertySourceConfigurationPropertySourceTests {
 	public void createWhenPropertySourceIsNullShouldThrowException() throws Exception {
 		this.thrown.expect(IllegalArgumentException.class);
 		this.thrown.expectMessage("PropertySource must not be null");
-		new PropertySourceConfigurationPropertySource(null, mock(PropertyMapper.class));
+		new PropertySourceConfigurationPropertySource(null, mock(PropertyMapper.class),
+				null);
 	}
 
 	@Test
 	public void createWhenMapperIsNullShouldThrowException() throws Exception {
 		this.thrown.expect(IllegalArgumentException.class);
 		this.thrown.expectMessage("Mapper must not be null");
-		new PropertySourceConfigurationPropertySource(mock(PropertySource.class), null);
+		new PropertySourceConfigurationPropertySource(mock(PropertySource.class), null,
+				null);
 	}
 
 	@Test
@@ -67,7 +69,7 @@ public class PropertySourceConfigurationPropertySourceTests {
 		ConfigurationPropertyName name = ConfigurationPropertyName.of("my.key");
 		mapper.addFromConfigurationProperty(name, "key2");
 		PropertySourceConfigurationPropertySource adapter = new PropertySourceConfigurationPropertySource(
-				propertySource, mapper);
+				propertySource, mapper, null);
 		assertThat(adapter.getConfigurationProperty(name).getValue()).isEqualTo("value2");
 	}
 
@@ -81,7 +83,7 @@ public class PropertySourceConfigurationPropertySourceTests {
 		mapper.addFromConfigurationProperty(name, "key",
 				(value) -> value.toString().replace("ue", "let"));
 		PropertySourceConfigurationPropertySource adapter = new PropertySourceConfigurationPropertySource(
-				propertySource, mapper);
+				propertySource, mapper, null);
 		assertThat(adapter.getConfigurationProperty(name).getValue()).isEqualTo("vallet");
 	}
 
@@ -94,7 +96,7 @@ public class PropertySourceConfigurationPropertySourceTests {
 		ConfigurationPropertyName name = ConfigurationPropertyName.of("my.key");
 		mapper.addFromConfigurationProperty(name, "key");
 		PropertySourceConfigurationPropertySource adapter = new PropertySourceConfigurationPropertySource(
-				propertySource, mapper);
+				propertySource, mapper, null);
 		assertThat(adapter.getConfigurationProperty(name).getOrigin().toString())
 				.isEqualTo("\"key\" from property source \"test\"");
 	}
@@ -109,11 +111,22 @@ public class PropertySourceConfigurationPropertySourceTests {
 		ConfigurationPropertyName name = ConfigurationPropertyName.of("my.key");
 		mapper.addFromConfigurationProperty(name, "key");
 		PropertySourceConfigurationPropertySource adapter = new PropertySourceConfigurationPropertySource(
-				propertySource, mapper);
+				propertySource, mapper, null);
 		assertThat(adapter.getConfigurationProperty(name).getOrigin().toString())
 				.isEqualTo("TestOrigin key");
 	}
 
+	@Test
+	public void containsDescendantOfShouldReturnEmpty() throws Exception {
+		Map<String, Object> source = new LinkedHashMap<>();
+		source.put("foo.bar", "value");
+		PropertySource<?> propertySource = new MapPropertySource("test", source);
+		PropertySourceConfigurationPropertySource adapter = new PropertySourceConfigurationPropertySource(
+				propertySource, new DefaultPropertyMapper(), null);
+		assertThat(adapter.containsDescendantOf(ConfigurationPropertyName.of("foo")))
+				.isEmpty();
+	}
+
 	/**
 	 * Test {@link PropertySource} that's also a {@link OriginLookup}.
 	 */

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

@@ -156,6 +156,23 @@ public class PropertySourceIterableConfigurationPropertySourceTests {
 				.isEqualTo("TestOrigin key");
 	}
 
+	@Test
+	public void containsDescendantOfShouldCheckSourceNames() throws Exception {
+		Map<String, Object> source = new LinkedHashMap<>();
+		source.put("foo.bar", "value");
+		source.put("faf", "value");
+		EnumerablePropertySource<?> propertySource = new OriginCapablePropertySource<>(
+				new MapPropertySource("test", source));
+		PropertySourceIterableConfigurationPropertySource adapter = new PropertySourceIterableConfigurationPropertySource(
+				propertySource, new DefaultPropertyMapper());
+		assertThat(adapter.containsDescendantOf(ConfigurationPropertyName.of("foo")))
+				.contains(true);
+		assertThat(adapter.containsDescendantOf(ConfigurationPropertyName.of("faf")))
+				.contains(false);
+		assertThat(adapter.containsDescendantOf(ConfigurationPropertyName.of("fof")))
+				.contains(false);
+	}
+
 	/**
 	 * Test {@link PropertySource} that's also a {@link OriginLookup}.
 	 */