update doc of ts-universal-events-drag-drop

Signed-off-by: Ndongzhanwu <dongzhanwu1@huawei.com>

zh-cn/application-dev/reference/arkui-ts/ts-universal-events-drag-drop.md

@@ -326,7 +326,6 @@ struct DragExample {
         console.log('List onDragLeave, ' + extraParams + 'X:' + event.getX() + 'Y:' + event.getY())
       })
       .onDrop((event: DragEvent, extraParams: string) => {
-        if (!extraParams.empty()) {
         let jsonString = JSON.parse(extraParams);
         if (this.bool) {
           // 通过splice方法插入元素
@@ -334,7 +333,6 @@ struct DragExample {
           this.bool = false
         }
         this.fruitVisible[this.idx] = Visibility.None
-        }
         this.getDataFromUDMFWithRetry(event);
       })
     }.width('100%').height('100%').padding({ top: 20 }).margin({ top: 20 })