Show custom non-working days in Jira calendar picker

Issue Summary

Adding custom holidays does not reflect in Jira calendar view
This is reproducible on Data Center: (yes)

Steps to Reproduce

Add custom holidays to your agile board

Suggestion

Selected "non-working days" in Board configuration could also be highlighted (in red?) in the calendar picker.

Current Results

Only the default Sat/Sun is highlighted in red. The chosen dates are reflected in the chart in the Reports view (and according gadget).