Update MQTT.cpp

Bug fix for #3382

src/mqtt/MQTT.cpp

@@ -185,7 +185,7 @@ MQTT::MQTT() : concurrency::OSThread("mqtt"), mqttQueue(MAX_MQTT_QUEUE)
             statusTopic = moduleConfig.mqtt.root + statusTopic;
             cryptTopic = moduleConfig.mqtt.root + cryptTopic;
             jsonTopic = moduleConfig.mqtt.root + jsonTopic;
-            mapTopic = moduleConfig.mqtt.root + jsonTopic;
+            mapTopic = moduleConfig.mqtt.root + mapTopic;
         } else {
             statusTopic = "msh" + statusTopic;
             cryptTopic = "msh" + cryptTopic;
@@ -915,4 +915,4 @@ bool MQTT::isValidJsonEnvelope(JSONObject &json)
            (json["from"]->AsNumber() == nodeDB.getNodeNum()) &&             // only accept message if the "from" is us
            (json.find("type") != json.end()) && json["type"]->IsString() && // should specify a type
            (json.find("payload") != json.end());                            // should have a payload
-}
+}