9 files declare their use of StreamWrapperInterface in Zircon Profile 8

BrowserTestBase.php in core/modules/simpletest/src/BrowserTestBase.php

Contains \Drupal\simpletest\BrowserTestBase.

editor.admin.inc in core/modules/editor/editor.admin.inc

Administration functions for editor.module.

FileItem.php in core/modules/file/src/Plugin/Field/FieldType/FileItem.php

Contains \Drupal\file\Plugin\Field\FieldType\FileItem.

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

Contains \Drupal\system\Form\FileSystemForm.

GDToolkit.php in core/modules/system/src/Plugin/ImageToolkit/GDToolkit.php

Contains \Drupal\system\Plugin\ImageToolkit\GDToolkit.

ImageItem.php in core/modules/image/src/Plugin/Field/FieldType/ImageItem.php

Contains \Drupal\image\Plugin\Field\FieldType\ImageItem.

ImageStyle.php in core/modules/image/src/Entity/ImageStyle.php

Contains \Drupal\image\Entity\ImageStyle.

KernelTestBase.php in core/modules/simpletest/src/KernelTestBase.php

Contains \Drupal\simpletest\KernelTestBase.

TranslationsStream.php in core/modules/locale/src/StreamWrapper/TranslationsStream.php

Contains \Drupal\locale\StreamWrapper\TranslationsStream.