`@extend .clearfix;` - typo?

[RoSk0]

Running stylelint over just copied from this project sass file I noticed this:

scss/drupal-bootstrap/component/_filter.scss
  ⚠  Expected a placeholder selector (e.g. %placeholder) to be used in @extend   scss/at-extend-no-missing-placeholder

drupal-bootstrap-styles/src/3.x.x/8.x-3.x/scss/drupal-bootstrap/component/_filter.scss

Line 15 in 9a9f753

@extend .clearfix;

I assume it refers to clearfix mixing from Bootstrap source files (bootstrap/assets/stylesheets/bootstrap/mixins/_clearfix.scss:13) then the line should be @extend .clearfix;?