I used the following simple template:

<noinclude>
<templatedata>
{
	"params": {
		"param1": {
			"default": "",
			"autovalue": "2",
			"suggested": true
		}
	}
}
</templatedata>
</noinclude>

Edit Source-> Manage TemplateData. In Template Documentation Editor

• change the value of 'Suggested' of param1 to zero - the changes won't be applied
• add 'Required' - the changes will be saved and applied
• try to change 'Required' value to zero - the changes are not saved/applied.