Introduce CompositePropertySource constructor that accepts Iterable<PropertySource>

This commit introduces a new constructor for CompositePropertySource
that accepts a `String name` and an Iterable<PropertySource<?>>, which
allows a CompositePropertySource to be constructed from existing
property sources, such as an instance of MutablePropertySources.

Closes gh-34862

Author: sbrannen

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,6 +39,7 @@
  * @author Chris Beams
  * @author Juergen Hoeller
  * @author Phillip Webb
+ * @author Sam Brannen
  * @since 3.1.1
  */
 public class CompositePropertySource extends EnumerablePropertySource<Object> {
@@ -47,13 +48,35 @@ public class CompositePropertySource extends EnumerablePropertySource<Object> {
 
 
 	/**
-	 * Create a new {@code CompositePropertySource}.
-	 * @param name the name of the property source
+	 * Create a new empty {@code CompositePropertySource} with the given name.
+	 * @param name the name of the composite property source
+	 * @see #CompositePropertySource(String, Iterable)
+	 * @see #addPropertySource(PropertySource)
+	 * @see #addFirstPropertySource(PropertySource)
 	 */
 	public CompositePropertySource(String name) {
 		super(name);
 	}
 
+	/**
+	 * Create a new {@code CompositePropertySource} with the given name and
+	 * property sources supplied as an {@link Iterable} or {@link PropertySources}
+	 * implementation, preserving the original order of the property sources.
+	 * @param name the name of the composite property source
+	 * @param propertySources the initial set of {@link PropertySource} instances
+	 * @since 6.2.7
+	 * @see PropertySources
+	 * @see MutablePropertySources
+	 * @see #addPropertySource(PropertySource)
+	 * @see #addFirstPropertySource(PropertySource)
+	 */
+	public CompositePropertySource(String name, Iterable<PropertySource<?>> propertySources) {
+		this(name);
+		for (PropertySource<?> propertySource : propertySources) {
+			this.propertySources.add(propertySource);
+		}
+	}
+
 
 	@Override
 	@Nullable