openproject/frontend/app/templates/plugin-costs/work_packages/cost_object.html

<span class="costs costObject" ng-if="!field.isEmpty()">
  <a ng-href="{{ linkToCostObject }}"
     title="{{ field.text.props.subject }}"
     aria-label ="{{ field.getKeyValue() }}">
    {{ field.text.props.subject }}
  </a>
</span>
<span ng-if="field.isEmpty()"
      work-package-accessible-attribute="field">
  {{field.placeholder}}
</span>