优化标签校验

jetlinks-manager/device-manager/src/main/java/org/jetlinks/community/device/entity/DeviceTagEntity.java

@@ -19,6 +19,7 @@ import javax.persistence.Column;
 import javax.persistence.Index;
 import javax.persistence.Table;
 import javax.validation.constraints.NotBlank;
+import javax.validation.constraints.NotNull;
 import java.util.Date;
 
 @Getter