Affects Version/s: 3.1.0-deprecated.18
1. Setup Liferay DXP 7.1.x
2. Start creating a new form
3. Add a Date element on it→Publish
4. Add a widget page
5. Add a language selector
6. Add the new form on it
7. Click on the element to show the date popup
8. Assert that the first weekday is Sun
9. Change the language to Swedish
10. Click on the element to show the date popup again
11. Check the day
The first day is for Monday.
The first day remained Sunday.
In other words, the client's problem is that the week is being rendered by the datepicker component starting on Sunday instead of Monday, therefore the combination of days in the calendar is also distributed incorrectly.
Alloy UI - https://alloyui.com/api/files/yui3_src_calendar_js_calendar-base.js.html#l40
YUI - https://clarle.github.io/yui3/yui/docs/api/files/calendar_js_calendar-base.js.html#l40
Liferay Language Support - https://grow.liferay.com/people/Language+Support
YUI Internationalization - https://clarle.github.io/yui3/yui/docs/intl/
Behavior in other portal versions:
7.2.x - Works as expected. The firstDay is set in a non-existent file in 7.1.x.