Set attributes on b-dropdown-group header

[aileen-r]

Is your feature request related to a problem? Please describe...

I am unable to set HTML attributes on the header element in b-dropdown-group.

Describe the solution you'd like

Similar to how b-dropdown offers the toggle-attrs prop, a header-attrs prop for b-dropdown-group that accepts an object which lets me set multiple attributes.

Describe alternatives you've considered

At the moment, I'm using b-dropdown-header separately. I would prefer to use b-dropdown-group for the accessibility benefits.

Additional context

My engineering team relies on data-test attributes for our automated test suites. We also use the title attribute a lot for providing extra context. This isn't the first BV component I've run into this issue with and it's one of the reasons we are starting to avoid using more BV in our component library.

It would be nice if exposing attributes was done by default in future. Thanks!