fix 线上课有教学点

mec-biz/src/main/java/com/ym/mec/biz/dal/entity/StudentVisit.java

@@ -86,7 +86,6 @@ public class StudentVisit {
      * 回访目的
      */
     @ApiModelProperty(value = "回访目的", required = true)
-    @NotBlank(message = "回访目的不能为空")
     private String purpose;
 
     /**