only get 20 records of KanbanHistory

kanban-console/src/main/java/com/uas/kanban/dao/KanbanHistoryDao.java

@@ -3,6 +3,7 @@ package com.uas.kanban.dao;
 import com.uas.kanban.annotation.NotEmpty;
 import com.uas.kanban.base.BaseDao;
 import com.uas.kanban.model.KanbanHistory;
+import org.mongodb.morphia.query.FindOptions;
 import org.mongodb.morphia.query.Query;
 import org.springframework.stereotype.Component;
 
@@ -27,7 +28,9 @@ public class KanbanHistoryDao extends BaseDao<KanbanHistory> {
         Query<KanbanHistory> query = createQuery();
         query.filter("kanbanCode", kanbanCode);
         query.filter("autoSaved", false);
-        return find(query);
+        FindOptions findOptions = new FindOptions();
+        findOptions.limit(20);
+        return query.asList(findOptions);
     }
 
     /**