added default configuration for tenant specific push notification provider

components/device-mgt-extensions/org.wso2.carbon.device.mgt.extensions.device.type.deployer/src/main/java/org/wso2/carbon/device/mgt/extensions/device/type/deployer/template/DeviceTypeManagerService.java

@@ -113,9 +113,13 @@ public class DeviceTypeManagerService implements DeviceManagementService {
         if (pushNotificationProvider != null) {
             if (pushNotificationProvider.isFileBasedProperties()) {
                 Map<String, String> staticProps = new HashMap<>();
+                if (pushNotificationProvider.getConfigProperties() != null &&
+                        pushNotificationProvider.getConfigProperties().getProperty() != null &&
+                        pushNotificationProvider.getConfigProperties().getProperty().size() > 0) {
                     for (Property property : pushNotificationProvider.getConfigProperties().getProperty()) {
                         staticProps.put(property.getName(), property.getValue());
                     }
+                }
                 pushNotificationConfig = new PushNotificationConfig(pushNotificationProvider.getType(),
                         pushNotificationProvider.isScheduled(), staticProps);
             } else {

components/device-mgt-extensions/org.wso2.carbon.device.mgt.extensions.push.notification.provider.mqtt/src/main/java/org/wso2/carbon/device/mgt/extensions/push/notification/provider/mqtt/MQTTNotificationStrategy.java

@@ -51,16 +51,14 @@ public class MQTTNotificationStrategy implements NotificationStrategy {
         this.config = config;
         OutputEventAdapterConfiguration adapterConfig = new OutputEventAdapterConfiguration();
         adapterConfig.setType(MQTTAdapterConstants.MQTT_ADAPTER_TYPE);
-        mqttAdapterName = config.getProperty(MQTTAdapterConstants.MQTT_ADAPTER_PROPERTY_NAME);
-
         adapterConfig.setMessageFormat(MessageType.TEXT);
 
         Map<String, String> configProperties = new HashMap<String, String>();
+        if (config.getProperties() != null && config.getProperties().size() > 0) {
             String brokerUrl = config.getProperty(MQTTAdapterConstants.MQTT_ADAPTER_PROPERTY_BROKER_URL);
             if (brokerUrl != null && !brokerUrl.isEmpty()) {
                 configProperties.put(MQTTAdapterConstants.MQTT_ADAPTER_PROPERTY_BROKER_URL, brokerUrl);
             }
-        if (config.getProperties() != null) {
             mqttAdapterName = config.getProperty(MQTTAdapterConstants.MQTT_ADAPTER_PROPERTY_NAME);
             configProperties.put(MQTTAdapterConstants.MQTT_ADAPTER_PROPERTY_USERNAME,
                                  config.getProperty(MQTTAdapterConstants.MQTT_ADAPTER_PROPERTY_USERNAME));
@@ -79,7 +77,14 @@ public class MQTTNotificationStrategy implements NotificationStrategy {
         adapterConfig.setName(mqttAdapterName);
         adapterConfig.setStaticProperties(configProperties);
         try {
+            synchronized (MQTTNotificationStrategy.class) {
+                try {
+                    MQTTDataHolder.getInstance().getOutputEventAdapterService().isPolled(mqttAdapterName);
+                } catch (OutputEventAdapterException e) {
+                    //event adapter not created
                     MQTTDataHolder.getInstance().getOutputEventAdapterService().create(adapterConfig);
+                }
+            }
         } catch (OutputEventAdapterException e) {
             throw new InvalidConfigurationException("Error occurred while initializing MQTT output event adapter", e);
         }