From ab944e6fdf5a324617fa6901fcdb0e2e736770ad Mon Sep 17 00:00:00 2001
From: Bao Tran <tran.bao51093@gmail.com>
Date: Sun, 14 May 2017 18:55:53 +0300
Subject: [PATCH] Fix duplicate subscriptionId for destination-sessionId key

Issue: SPR-15543
---
 .../messaging/simp/broker/DefaultSubscriptionRegistry.java  | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistry.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistry.java
index f6d8c455f44d..319907280581 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistry.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistry.java
@@ -292,8 +292,10 @@ public void updateAfterNewSubscription(String destination, String sessionId, Str
 					String cachedDestination = entry.getKey();
 					if (getPathMatcher().match(destination, cachedDestination)) {
 						LinkedMultiValueMap<String, String> subs = entry.getValue();
-						subs.add(sessionId, subsId);
-						this.accessCache.put(cachedDestination, subs.deepCopy());
+						if (!subs.containsKey(sessionId) || !subs.get(sessionId).contains(subsId)) {
+							subs.add(sessionId, subsId);
+							this.accessCache.put(cachedDestination, subs.deepCopy());
+						}
 					}
 				}
 			}