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 7345ff4dff9..4c0553f0e4a 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
@@ -17,8 +17,8 @@
 package org.springframework.core.env;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
@@ -90,7 +90,7 @@ public class CompositePropertySource extends EnumerablePropertySource<Object> {
 			total += names.length;
 		}
 		Set<String> allNames = new LinkedHashSet<>(total);
-		namesList.forEach(names -> allNames.addAll(Arrays.asList(names)));
+		namesList.forEach(names -> Collections.addAll(allNames, names));
 		return StringUtils.toStringArray(allNames);
 	}
 
diff --git a/spring-core/src/test/java/org/springframework/core/env/CompositePropertySourceTests.java b/spring-core/src/test/java/org/springframework/core/env/CompositePropertySourceTests.java
index fba8bd2aa5d..773e9bcfdb2 100644
--- a/spring-core/src/test/java/org/springframework/core/env/CompositePropertySourceTests.java
+++ b/spring-core/src/test/java/org/springframework/core/env/CompositePropertySourceTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -16,7 +16,6 @@
 
 package org.springframework.core.env;
 
-import java.util.Collections;
 import java.util.Map;
 
 import org.junit.jupiter.api.Test;
@@ -27,24 +26,23 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for {@link CompositePropertySource}.
  *
  * @author Phillip Webb
+ * @author Sam Brannen
  */
 class CompositePropertySourceTests {
 
 	@Test
 	void addFirst() {
-		PropertySource<?> p1 = new MapPropertySource("p1", Collections.emptyMap());
-		PropertySource<?> p2 = new MapPropertySource("p2", Collections.emptyMap());
-		PropertySource<?> p3 = new MapPropertySource("p3", Collections.emptyMap());
+		PropertySource<?> p1 = new MapPropertySource("p1", Map.of());
+		PropertySource<?> p2 = new MapPropertySource("p2", Map.of());
+		PropertySource<?> p3 = new MapPropertySource("p3", Map.of());
 		CompositePropertySource composite = new CompositePropertySource("c");
 		composite.addPropertySource(p2);
 		composite.addPropertySource(p3);
 		composite.addPropertySource(p1);
 		composite.addFirstPropertySource(p1);
-		String s = composite.toString();
-		int i1 = s.indexOf("name='p1'");
-		int i2 = s.indexOf("name='p2'");
-		int i3 = s.indexOf("name='p3'");
-		assertThat(((i1 < i2) && (i2 < i3))).as("Bad order: " + s).isTrue();
+
+		assertThat(composite.getPropertySources()).extracting(PropertySource::getName).containsExactly("p1", "p2", "p3");
+		assertThat(composite).asString().containsSubsequence("name='p1'", "name='p2'", "name='p3'");
 	}
 
 	@Test