added test

application/src/main/java/org/thingsboard/server/service/entitiy/SimpleTbEntityService.java

@@ -26,6 +26,6 @@ public interface SimpleTbEntityService<T> {
 
     T save(T entity, User user) throws Exception;
 
-    void delete(T entity, User user) throws ThingsboardException;
+    void delete(T entity, User user);
 
 }

application/src/main/java/org/thingsboard/server/service/resource/DefaultTbResourceService.java

@@ -151,15 +151,10 @@ public class DefaultTbResourceService extends AbstractTbEntityService implements
     }
 
     @Override
-    public void delete(TbResource tbResource, User user) throws ThingsboardException {
+    public void delete(TbResource tbResource, User user) {
         TbResourceId resourceId = tbResource.getId();
         TenantId tenantId = tbResource.getTenantId();
         try {
-            List<WidgetTypeDetails> widgets = widgetTypeService.findWidgetTypesInfosByTenantIdAndResourceId(tenantId, resourceId);
-            if (!widgets.isEmpty()) {
-                List<String> widgetNames = widgets.stream().map(BaseWidgetType::getName).collect(Collectors.toList());
-                throw new ThingsboardException(String.format("Following widget types uses current resource: %s", widgetNames), ThingsboardErrorCode.GENERAL);
-            }
             resourceService.deleteResource(tenantId, resourceId);
             tbClusterService.onResourceDeleted(tbResource, null);
             notificationEntityService.logEntityAction(tenantId, resourceId, tbResource, ActionType.DELETED, user, resourceId.toString());

application/src/test/java/org/thingsboard/server/controller/TbResourceControllerTest.java

@@ -38,6 +38,8 @@ import org.thingsboard.server.common.data.audit.ActionType;
 import org.thingsboard.server.common.data.page.PageData;
 import org.thingsboard.server.common.data.page.PageLink;
 import org.thingsboard.server.common.data.security.Authority;
+import org.thingsboard.server.common.data.widget.WidgetTypeDetails;
+import org.thingsboard.server.common.data.widget.WidgetsBundle;
 import org.thingsboard.server.dao.exception.DataValidationException;
 import org.thingsboard.server.dao.service.DaoSqlTest;
 
@@ -216,6 +218,36 @@ public class TbResourceControllerTest extends AbstractControllerTest {
                 .andExpect(statusReason(containsString(msgErrorNoFound("Resource", resourceIdStr))));
     }
 
+    @Test
+    public void testShoudNotDeleteTbResourceIfAssignedToWidgetType() throws Exception {
+        TbResource resource = new TbResource();
+        resource.setResourceType(ResourceType.JKS);
+        resource.setTitle("My first resource");
+        resource.setFileName(DEFAULT_FILE_NAME);
+        resource.setData(TEST_DATA);
+
+        TbResource savedResource = save(resource);
+
+        Mockito.reset(tbClusterService, auditLogService);
+        String resourceIdStr = savedResource.getId().getId().toString();
+
+        //create widget type
+        WidgetsBundle widgetsBundle = new WidgetsBundle();
+        widgetsBundle.setTitle("My widgets bundle");
+        WidgetsBundle savedWidgetsBundle = doPost("/api/widgetsBundle", widgetsBundle, WidgetsBundle.class);
+
+        WidgetTypeDetails widgetType = new WidgetTypeDetails();
+        widgetType.setBundleAlias(savedWidgetsBundle.getAlias());
+        widgetType.setName("Widget Type");
+        widgetType.setDescriptor(JacksonUtil.fromString(String.format("{ \"resources\": [{\"url\":{\"entityType\":\"TB_RESOURCE\",\"id\":\"%s\"},\"isModule\":true}]}", savedResource.getId()), JsonNode.class));
+        doPost("/api/widgetType", widgetType, WidgetTypeDetails.class);
+
+        doDelete("/api/resource/" + resourceIdStr)
+                .andExpect(status().isBadRequest())
+                .andExpect(statusReason(containsString("Following widget types uses current resource: ["
+                        + widgetType .getName()+ "]")));
+    }
+
     @Test
     public void testFindTenantTbResources() throws Exception {
 

dao/src/main/java/org/thingsboard/server/dao/resource/BaseResourceService.java

@@ -109,6 +109,7 @@ public class BaseResourceService extends AbstractCachedEntityService<ResourceInf
     public void deleteResource(TenantId tenantId, TbResourceId resourceId) {
         log.trace("Executing deleteResource [{}] [{}]", tenantId, resourceId);
         Validator.validateId(resourceId, INCORRECT_RESOURCE_ID + resourceId);
+        resourceValidator.validateDelete(tenantId, resourceId);
         resourceDao.removeById(tenantId, resourceId.getId());
     }
 

dao/src/main/java/org/thingsboard/server/dao/service/DataValidator.java

@@ -22,6 +22,7 @@ import org.springframework.context.annotation.Lazy;
 import org.thingsboard.server.common.data.BaseData;
 import org.thingsboard.server.common.data.EntityType;
 import org.thingsboard.server.common.data.StringUtils;
+import org.thingsboard.server.common.data.id.EntityId;
 import org.thingsboard.server.common.data.id.TenantId;
 import org.thingsboard.server.dao.TenantEntityWithDataDao;
 import org.thingsboard.server.dao.exception.DataValidationException;
@@ -82,6 +83,9 @@ public abstract class DataValidator<D extends BaseData<?>> {
         return null;
     }
 
+    public void validateDelete(TenantId tenantId, EntityId entityId) {
+    }
+
     protected boolean isSameData(D existentData, D actualData) {
         return actualData.getId() != null && existentData.getId().equals(actualData.getId());
     }

dao/src/main/java/org/thingsboard/server/dao/service/validator/ResourceDataValidator.java

@@ -20,14 +20,21 @@ import org.springframework.context.annotation.Lazy;
 import org.springframework.stereotype.Component;
 import org.thingsboard.server.common.data.StringUtils;
 import org.thingsboard.server.common.data.TbResource;
+import org.thingsboard.server.common.data.id.EntityId;
 import org.thingsboard.server.common.data.id.TenantId;
 import org.thingsboard.server.common.data.tenant.profile.DefaultTenantProfileConfiguration;
+import org.thingsboard.server.common.data.widget.BaseWidgetType;
+import org.thingsboard.server.common.data.widget.WidgetTypeDetails;
 import org.thingsboard.server.dao.exception.DataValidationException;
 import org.thingsboard.server.dao.model.ModelConstants;
 import org.thingsboard.server.dao.resource.TbResourceDao;
 import org.thingsboard.server.dao.service.DataValidator;
 import org.thingsboard.server.dao.tenant.TbTenantProfileCache;
 import org.thingsboard.server.dao.tenant.TenantService;
+import org.thingsboard.server.dao.widget.WidgetTypeDao;
+
+import java.util.List;
+import java.util.stream.Collectors;
 
 import static org.thingsboard.server.common.data.EntityType.TB_RESOURCE;
 
@@ -37,6 +44,9 @@ public class ResourceDataValidator extends DataValidator<TbResource> {
     @Autowired
     private TbResourceDao resourceDao;
 
+    @Autowired
+    private WidgetTypeDao widgetTypeDao;
+
     @Autowired
     private TenantService tenantService;
 
@@ -77,4 +87,15 @@ public class ResourceDataValidator extends DataValidator<TbResource> {
             }
         }
     }
+
+    @Override
+    public void validateDelete(TenantId tenantId, EntityId resourceId) {
+        List<WidgetTypeDetails> widgets = widgetTypeDao.findWidgetTypesInfosByTenantIdAndResourceId(tenantId.getId(),
+                resourceId.getId());
+        if (!widgets.isEmpty()) {
+            List<String> widgetNames = widgets.stream().map(BaseWidgetType::getName).collect(Collectors.toList());
+            throw new DataValidationException(String.format("Following widget types uses current resource: %s", widgetNames));
+        }
+    }
+
 }