Bug in collapsed class on accordion title panel

Default collapsed accordion title panel has no 'collapsed' class

Code responsible to add 'collapsed' class isn't working and small fix is needed in views-bootstrap-accordion-plugin-style.tpl.php file.

Code

    $expanded = (($loop_count == 1 && $behavior == 'first') || $behavior == 'all') ? 'true' : 'false';
    $title_classes = 'accordion-toggle';
    $title_classes .= $expanded ? '' : ' collapsed';

must be fixed because any string of 'true' or 'false' will be cast to boolean .

I would like to suggest fix for it

    $expanded = (($loop_count == 1 && $behavior == 'first') || $behavior == 'all') ? 'true' : 'false';
    $title_classes = 'accordion-toggle';
    $title_classes .= $expanded == 'true' ? '' : ' collapsed';

I use it in template of my own custom theme so patch is not needed in my case but it is worth making a patch.