Minor refactoring for user notification settings

application/src/main/java/org/thingsboard/server/controller/NotificationController.java

@@ -298,7 +298,7 @@ public class NotificationController extends BaseController {
             if (targetType == NotificationTargetType.PLATFORM_USERS) {
                 PageData<User> recipients = notificationTargetService.findRecipientsForNotificationTargetConfig(user.getTenantId(),
                         (PlatformUsersNotificationTargetConfig) target.getConfiguration(), new PageLink(recipientsPreviewSize, 0, null,
-                                SortOrder.byCreatedTimeDesc));
+                                SortOrder.BY_CREATED_TIME_DESC));
                 recipientsCount = (int) recipients.getTotalElements();
                 recipientsPart = recipients.getData().stream().map(r -> (NotificationRecipient) r).collect(Collectors.toList());
             } else {

common/data/src/main/java/org/thingsboard/server/common/data/page/SortOrder.java

@@ -36,6 +36,6 @@ public class SortOrder {
         ASC, DESC
     }
 
-    public static final SortOrder byCreatedTimeDesc = new SortOrder("createdTime", Direction.DESC);
+    public static final SortOrder BY_CREATED_TIME_DESC = new SortOrder("createdTime", Direction.DESC);
 
 }

dao/src/main/java/org/thingsboard/server/dao/notification/DefaultNotificationSettingsService.java

@@ -16,6 +16,7 @@
 package org.thingsboard.server.dao.notification;
 
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.springframework.cache.annotation.CacheEvict;
 import org.springframework.cache.annotation.Cacheable;
 import org.springframework.stereotype.Service;
@@ -55,6 +56,7 @@ import java.util.Optional;
 
 @Service
 @RequiredArgsConstructor
+@Slf4j
 public class DefaultNotificationSettingsService implements NotificationSettingsService {
 
     private final AdminSettingsService adminSettingsService;
@@ -104,10 +106,15 @@ public class DefaultNotificationSettingsService implements NotificationSettingsS
     @Override
     public UserNotificationSettings getUserNotificationSettings(TenantId tenantId, UserId userId, boolean format) {
         UserSettings userSettings = userSettingsService.findUserSettings(tenantId, userId, UserSettingsType.NOTIFICATIONS);
-        UserNotificationSettings settings;
+        UserNotificationSettings settings = null;
         if (userSettings != null) {
-            settings = JacksonUtil.treeToValue(userSettings.getSettings(), UserNotificationSettings.class);
-        } else {
+            try {
+                settings = JacksonUtil.treeToValue(userSettings.getSettings(), UserNotificationSettings.class);
+            } catch (Exception e) {
+                log.warn("Failed to parse notification settings for user {}", userId, e);
+            }
+        }
+        if (settings == null) {
             settings = UserNotificationSettings.DEFAULT;
         }
         if (format) {