From b3051a136aa2e5dd8f59b267ee4afee33b84fc58 Mon Sep 17 00:00:00 2001
From: Marcin Grzejszczak <marcin.grzejszczak@gmail.com>
Date: Wed, 9 Dec 2020 14:57:00 +0100
Subject: [PATCH] Passing a copy of headers - otherwise
 ConcurrentModificationException may happen

fixes gh-1184
---
 .../sleuth/instrument/messaging/TracingChannelInterceptor.java  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/messaging/TracingChannelInterceptor.java b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/messaging/TracingChannelInterceptor.java
index 51398b627..28b06b396 100644
--- a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/messaging/TracingChannelInterceptor.java
+++ b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/messaging/TracingChannelInterceptor.java
@@ -259,7 +259,7 @@ public final class TracingChannelInterceptor extends ChannelInterceptorAdapter
 							: new MessageHeaders(headers.getMessageHeaders()),
 					errorMessage.getOriginalMessage());
 		}
-		headers.copyHeaders(additionalHeaders.getMessageHeaders());
+		headers.copyHeaders(new MessageHeaders(additionalHeaders.getMessageHeaders()));
 		return new GenericMessage<>(retrievedMessage.getPayload(),
 				isWebSockets(headers) ? headers.getMessageHeaders()
 						: new MessageHeaders(headers.getMessageHeaders()));