12 files declare their use of ServiceModifierInterface in Drupal 9

AcceptHeaderRoutingTestServiceProvider.php in core/modules/system/tests/modules/accept_header_routing_test/src/AcceptHeaderRoutingTestServiceProvider.php

ContainerRebuildTestServiceProvider.php in core/modules/system/tests/modules/container_rebuild_test/src/ContainerRebuildTestServiceProvider.php

CoreServiceProvider.php in core/lib/Drupal/Core/CoreServiceProvider.php

DrupalKernel.php in core/lib/Drupal/Core/DrupalKernel.php

ErrorServiceTestServiceProvider.php in core/modules/system/tests/modules/error_service_test/src/ErrorServiceTestServiceProvider.php

FileServiceProvider.php in core/modules/file/src/FileServiceProvider.php

HalServiceProvider.php in core/modules/hal/src/HalServiceProvider.php

InstallerServiceProvider.php in core/lib/Drupal/Core/Installer/InstallerServiceProvider.php

JsonapiServiceProvider.php in core/modules/jsonapi/src/JsonapiServiceProvider.php

ModifyServiceDefinitionsPass.php in core/lib/Drupal/Core/DependencyInjection/Compiler/ModifyServiceDefinitionsPass.php

ServiceProviderTestServiceProvider.php in core/modules/system/tests/modules/service_provider_test/src/ServiceProviderTestServiceProvider.php

UpdateServiceProvider.php in core/lib/Drupal/Core/Update/UpdateServiceProvider.php