fix: 网管状态信息返回nil字符修改

src/modules/oam/controller/api_rest.go

@@ -681,7 +681,11 @@ func (s APIRestController) QuerySystemState(c *gin.Context) {
 		c.JSON(200, resp.ErrMsg("elementType only omc"))
 		return
 	}
-	c.JSON(200, goOamState.NewState.Info())
+	info := goOamState.NewState.Info()
+	info.SerialNum = "-"
+	info.ExpiryDate = "-"
+	info.Capability = 50
+	c.JSON(200, info)
 }
 
 // NeConfigOMC 网元配置对端网管信息