fix 系统回复

zhongzheng-admin/src/main/java/com/zhongzheng/controller/user/UserCourseAnswerController.java

@@ -54,6 +54,10 @@ public class UserCourseAnswerController extends BaseController {
     @Log(title = "答疑", businessType = BusinessType.INSERT)
     @PostMapping()
     public AjaxResult<Void> add(@RequestBody UserCourseAnswerAddBo bo) {
+        if(bo.getUserId().longValue()==0){
+            //默认系统用户1
+            bo.setUserId(1L);
+        }
         return toAjax(iUserCourseAnswerService.insertByAddBo(bo) ? 1 : 0);
     }