CompositePropertySource allows for access to its nested property sources

Issue: SPR-12182

spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java

@@ -17,6 +17,7 @@
 package org.springframework.core.env;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
@@ -75,6 +76,14 @@ public void addFirstPropertySource(PropertySource<?> propertySource) {
 		this.propertySources.addAll(existing);
 	}
 
+	/**
+	 * Return all property sources that this composite source holds.
+	 * @since 4.1.1
+	 */
+	public Collection<PropertySource<?>> getPropertySources() {
+		return this.propertySources;
+	}
+
 	@Override
 	public String toString() {
 		return String.format("%s [name='%s', propertySources=%s]",