From 16909584c336b6e5a58434629494be6ca7477b52 Mon Sep 17 00:00:00 2001
From: "Otavio R. Piske" <angusyoung@gmail.com>
Date: Thu, 21 Feb 2019 19:33:07 +0100
Subject: [PATCH] ARTEMIS-1952 NPE logged at warn if MQTT subscriber
 disconnects abruptly

Prevent a NullPointerException if no connection by the given clientId is
found on the cache of stored sessions
---
 .../artemis/core/protocol/mqtt/MQTTProtocolManager.java   | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/artemis-protocols/artemis-mqtt-protocol/src/main/java/org/apache/activemq/artemis/core/protocol/mqtt/MQTTProtocolManager.java b/artemis-protocols/artemis-mqtt-protocol/src/main/java/org/apache/activemq/artemis/core/protocol/mqtt/MQTTProtocolManager.java
index c8832bafaa..71d30d8492 100644
--- a/artemis-protocols/artemis-mqtt-protocol/src/main/java/org/apache/activemq/artemis/core/protocol/mqtt/MQTTProtocolManager.java
+++ b/artemis-protocols/artemis-mqtt-protocol/src/main/java/org/apache/activemq/artemis/core/protocol/mqtt/MQTTProtocolManager.java
@@ -179,7 +179,13 @@ class MQTTProtocolManager extends AbstractProtocolManager<MqttMessage, MQTTInter
    }
 
    public boolean isClientConnected(String clientId, MQTTConnection connection) {
-      return connectedClients.get(clientId).equals(connection);
+      MQTTConnection connectedConn = connectedClients.get(clientId);
+
+      if (connectedConn != null) {
+         return connectedConn.equals(connection);
+      }
+
+      return false;
    }
 
    public void removeConnectedClient(String clientId) {