From aeaad006cd926f7c6742c270da1ce96f4d3228df Mon Sep 17 00:00:00 2001
From: dugenkui03 <dugk@foxmail.com>
Date: Sat, 16 Apr 2022 21:21:18 +0800
Subject: [PATCH] Make event handling in ClassPathFileSystemWatcherTests
 thread-safe

See gh-30844
---
 .../devtools/classpath/ClassPathFileSystemWatcherTests.java    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/classpath/ClassPathFileSystemWatcherTests.java b/spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/classpath/ClassPathFileSystemWatcherTests.java
index 1bd8ba26faa..146f542e966 100644
--- a/spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/classpath/ClassPathFileSystemWatcherTests.java
+++ b/spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/classpath/ClassPathFileSystemWatcherTests.java
@@ -23,6 +23,7 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
@@ -116,7 +117,7 @@ class ClassPathFileSystemWatcherTests {
 
 	static class Listener implements ApplicationListener<ClassPathChangedEvent> {
 
-		private List<ClassPathChangedEvent> events = new ArrayList<>();
+		private List<ClassPathChangedEvent> events = new CopyOnWriteArrayList<>();
 
 		@Override
 		public void onApplicationEvent(ClassPathChangedEvent event) {