Fix compilation error

analytics/includes/AnalyzerConfiguratorTemplate.h

@@ -111,7 +111,7 @@ public:
     */
     void printConfig(LOG_LEVEL ll) final {
         LOG_VAR(ll) << "    General: ";
-        LOG_VAR(ll) << "          MQTT-Prefix:    " << (_mqttPrefix != "" ? _mqttPrefix : "DEFAULT");
+        LOG_VAR(ll) << "          MQTT-Prefix:    " << (_mqttPrefix != "" ? _mqttPrefix : std::string("DEFAULT"));
         LOG_VAR(ll) << "          CacheInterval: " << _cacheInterval/1000 << " [s]";
 
         //prints plugin specific configurator attributes and entities if present