How to make Date custom field with date selector?

How to make Date custom field with date selector?

        <customfield-type key="issuestartdate" name="Issue Start Date" class="com.atlassian.jira.issue.customfields.impl.DateCFType">
	    <description>Start date for issues to use Gantt Chart.</description>
		<resource type="velocity" name="edit" location="edit-issuestartdate.vm"/>
	</customfield-type>

“Date picker” JIRA custom field already goes with the picker:

If you still need to create you own datepicker with own renderer, you can check JIRA sources of the “Date picker” field.

Which folder I find that source code?

Search through the sources for “datepicker-input” gives me velocity: atlassian-jira-software-7.1.6-source/jira-project/jira-components/jira-core/src/main/resources/templates/plugins/fields/edit/edit-datepicker.vm