avoided null check when comparing

components/iot-plugins/virtual-fire-alarm-plugin/org.wso2.carbon.device.mgt.iot.virtualfirealarm.plugin/src/main/java/org/wso2/carbon/device/mgt/iot/virtualfirealarm/plugin/xmpp/XmppConfig.java

@@ -45,7 +45,7 @@ public class XmppConfig {
         List<PushNotificationConfig.Property> properties = deviceManagementConfiguration.getPushNotificationConfig()
                 .getProperties();
         String provider = deviceManagementConfiguration.getPushNotificationConfig().getPushNotificationProvider();
-        if (provider.equals("XMPP")) {
+        if ("XMPP".equals(provider)) {
             enabled = true;
         }
         if (enabled) {