fix: redis cache exception

@@ -12,7 +12,7 @@ import org.thingsboard.server.common.data.yunteng.enums.AreaLevelEnum;
  */
 @Data
 @ApiModel(value = "中国省市区街关联")
-public class SysAreaDTO {
+public class SysAreaDTO implements Serializable {
     @ApiModelProperty(value = "上级Code")
     private Long parentId;
 

@@ -29,7 +29,6 @@ public class SysAreaServiceImpl implements SysAreaService {
 
   @Override
   public List<SysAreaDTO> list(SysAreaDTO sysAreaDTO) {
-    cacheManager.getCache(FastIotConstants.CacheKey.area).get(sysAreaDTO.getParentId());
     List<SysAreaDTO> result = cacheManager.getCache(FastIotConstants.CacheKey.area).get(sysAreaDTO.getParentId(),List.class);
     if(result == null || result.isEmpty()){
       result = ReflectUtils.sourceToTarget(