How do i apply validation in widget level when datatype is Date?data

Hi,


I read below URL for adding an element on the widget:-

https://community.telligent.com/community/9/w/developer-training/52490/supporting-configuration

But didn't get a solution for my query. 

Whenever I open and save widget without entering a date. It saved widget without a date. My requirement is when a user selects start date then the event should occur on DOM otherwise it shouldn't show. Date can't empty. It should always check date if it is visible.
I applied few things which are below:-

<property use="required" pattern="\d{1,2}/\d{1,2}/\d{4}" id="startdate"  dataType="date" resourceName="CF_Start_Date" value="start_date" />