7 files declare their use of PathValidatorInterface in Drupal 8

ContactFormEditForm.php in core/modules/contact/src/ContactFormEditForm.php

LinkFormatter.php in core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php

MenuLinkContentForm.php in core/modules/menu_link_content/src/Form/MenuLinkContentForm.php

Route.php in core/modules/migrate/src/Plugin/migrate/process/Route.php

ShortcutSetController.php in core/modules/shortcut/src/Controller/ShortcutSetController.php

SiteInformationForm.php in core/modules/system/src/Form/SiteInformationForm.php

ValidPathConstraintValidator.php in core/lib/Drupal/Core/Path/Plugin/Validation/Constraint/ValidPathConstraintValidator.php