diff --git a/spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java b/spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java
index 6ce1d0d7794..07ddbaed6a5 100644
--- a/spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java
+++ b/spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java
@@ -17,21 +17,29 @@
package org.springframework.core.env;
import java.util.ArrayList;
+import java.util.Arrays;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
+import org.springframework.util.StringUtils;
+
/**
* Composite {@link PropertySource} implementation that iterates over a set of
* {@link PropertySource} instances. Necessary in cases where multiple property sources
* share the same name, e.g. when multiple values are supplied to {@code @PropertySource}.
*
+ *
As of Spring 4.1.2, this class extends {@link EnumerablePropertySource} instead
+ * of plain {@link PropertySource}, exposing {@link #getPropertyNames()} based on the
+ * accumulated property names from all contained sources (as far as possible).
+ *
* @author Chris Beams
+ * @author Juergen Hoeller
* @author Phillip Webb
* @since 3.1.1
*/
-public class CompositePropertySource extends PropertySource