ui-select/src/select2/choices.tpl.html

<ul tabindex="-1" class="ui-select-choices ui-select-choices-content select2-results">
  <li class="ui-select-choices-group" ng-class="{'select2-result-with-children': $select.choiceGrouped($group) }">
    <div ng-show="$select.choiceGrouped($group)" class="ui-select-choices-group-label select2-result-label" ng-bind="$group.name"></div>
    <ul
      id="ui-select-choices-{{ $select.generatedId }}" ng-class="{'select2-result-sub': $select.choiceGrouped($group), 'select2-result-single': !$select.choiceGrouped($group) }">
      <li role="option" ng-attr-id="ui-select-choices-row-{{ $select.generatedId }}-{{$index}}" class="ui-select-choices-row" ng-class="{'select2-highlighted': $select.isActive(this), 'select2-disabled': $select.isDisabled(this)}">
        <div class="select2-result-label ui-select-choices-row-inner"></div>
      </li>
    </ul>
  </li>
</ul>