Jira Issue Calendar Gadget considering GMT instead of the default user time zone for Date Time Picker values

Summary

When we set a Date Time Picker in an issue, it will show fine in the view issue screen. However, Jira Issue Calendar gadget can show the issue on a wrong date, depending on the Default user time zone set in the instance.

Environment

• JIRA Cloud

Steps to Reproduce

1. Set the Default user time zone of the instance to i.e. GMT-5;
2. Set the date in a Date Time Picker custom field (upon creation) to be Dez 11, at 7 pm;
3. In the Calendar gadget the issue shows on Dez 12;
4. If we check the date and time in the database, Jira seems to be considering the GMT (Z) instead of the users' GMT.

Expected Results

• Calendar gadget shows the date as Dez 11.

Actual Results

• Calendar gadget shows then date as Dez 12.

Workaround

None at the moment.