57 files declare their use of MessengerInterface

AjaxFormBlock.php in core/modules/system/tests/modules/ajax_forms_test/src/Plugin/Block/AjaxFormBlock.php
AreaDisplayLinkTest.php in core/modules/views/tests/src/Kernel/Handler/AreaDisplayLinkTest.php
BanAdminTest.php in core/modules/ban/tests/src/Unit/BanAdminTest.php
BigPipe.php in core/modules/big_pipe/src/Render/BigPipe.php
BlockListBuilder.php in core/modules/block/src/BlockListBuilder.php
BulkForm.php in core/modules/views/src/Plugin/views/field/BulkForm.php
CKEditor5.php in core/modules/ckeditor5/src/Plugin/Editor/CKEditor5.php
ContentModerationConfigureEntityTypesForm.php in core/modules/content_moderation/src/Form/ContentModerationConfigureEntityTypesForm.php
ContentTranslationHandler.php in core/modules/content_translation/src/ContentTranslationHandler.php
Cookie.php in core/modules/user/src/Authentication/Provider/Cookie.php
DeleteMultipleForm.php in core/lib/Drupal/Core/Entity/Form/DeleteMultipleForm.php
DiscardLayoutChangesForm.php in core/modules/layout_builder/src/Form/DiscardLayoutChangesForm.php
EntityReference.php in core/modules/views/src/Plugin/views/filter/EntityReference.php
EntityReferenceAdminTest.php in core/modules/field/tests/src/Functional/EntityReference/EntityReferenceAdminTest.php
FiberPlaceholderTest.php in core/modules/big_pipe/tests/src/Unit/Render/FiberPlaceholderTest.php
file.module in core/modules/file/file.module
Defines a "managed_file" Form API field and a "file" field for Field module.
FileImageDimensionsConstraintValidator.php in core/modules/file/src/Plugin/Validation/Constraint/FileImageDimensionsConstraintValidator.php
FileSaveUploadTest.php in core/modules/file/tests/src/Kernel/FileSaveUploadTest.php
FileTestSaveUploadFromForm.php in core/modules/file/tests/file_test/src/Form/FileTestSaveUploadFromForm.php
FilterFormatListBuilder.php in core/modules/filter/src/FilterFormatListBuilder.php
FormAjaxSubscriber.php in core/lib/Drupal/Core/Form/EventSubscriber/FormAjaxSubscriber.php
FormAjaxSubscriberTest.php in core/tests/Drupal/Tests/Core/Form/EventSubscriber/FormAjaxSubscriberTest.php
FormErrorHandler.php in core/modules/inline_form_errors/src/FormErrorHandler.php
FormErrorHandlerTest.php in core/tests/Drupal/Tests/Core/Form/FormErrorHandlerTest.php
FormErrorHandlerTest.php in core/modules/inline_form_errors/tests/src/Unit/FormErrorHandlerTest.php
HelpSearch.php in core/modules/help/src/Plugin/Search/HelpSearch.php
LanguageListBuilder.php in core/modules/language/src/LanguageListBuilder.php
LayoutBuilderDisableForm.php in core/modules/layout_builder/src/Form/LayoutBuilderDisableForm.php
MailTest.php in core/modules/system/tests/src/Kernel/Mail/MailTest.php
MaintenanceModeSubscriber.php in core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
ManyPlaceholderTest.php in core/modules/big_pipe/tests/src/Unit/Render/ManyPlaceholderTest.php
MessageAction.php in core/lib/Drupal/Core/Action/Plugin/Action/MessageAction.php
MessengerTest.php in core/tests/Drupal/KernelTests/Core/Messenger/MessengerTest.php
MigrationState.php in core/modules/migrate_drupal/src/MigrationState.php
MigrationStateUnitTest.php in core/modules/migrate_drupal/tests/src/Unit/MigrationStateUnitTest.php
ModerationOptOutPublish.php in core/modules/content_moderation/src/Plugin/Action/ModerationOptOutPublish.php
ModerationOptOutUnpublish.php in core/modules/content_moderation/src/Plugin/Action/ModerationOptOutUnpublish.php
NodeSearch.php in core/modules/node/src/Plugin/Search/NodeSearch.php
OEmbed.php in core/modules/media/src/Plugin/media/Source/OEmbed.php
OEmbedFormatter.php in core/modules/media/src/Plugin/Field/FieldFormatter/OEmbedFormatter.php
PrepareLayout.php in core/modules/layout_builder/src/EventSubscriber/PrepareLayout.php
RevertOverridesForm.php in core/modules/layout_builder/src/Form/RevertOverridesForm.php
RevisionDeleteForm.php in core/lib/Drupal/Core/Entity/Form/RevisionDeleteForm.php
RevisionRevertForm.php in core/lib/Drupal/Core/Entity/Form/RevisionRevertForm.php
RoleListBuilder.php in core/modules/user/src/RoleListBuilder.php
SearchPageListBuilder.php in core/modules/search/src/SearchPageListBuilder.php
SmartDefaultSettings.php in core/modules/ckeditor5/src/SmartDefaultSettings.php
Sql.php in core/modules/views/src/Plugin/views/query/Sql.php
SqlTest.php in core/modules/views/tests/src/Unit/Plugin/query/SqlTest.php
SystemTestController.php in core/modules/system/tests/modules/system_test/src/Controller/SystemTestController.php
TestPrepareLayout.php in core/modules/layout_builder/tests/modules/layout_builder_element_test/src/EventSubscriber/TestPrepareLayout.php
UpdateSettingsFormTest.php in core/modules/update/tests/src/Functional/UpdateSettingsFormTest.php
UserMultipleCancelConfirm.php in core/modules/user/src/Form/UserMultipleCancelConfirm.php
VocabularyListBuilder.php in core/modules/taxonomy/src/VocabularyListBuilder.php
WorkspaceActivateForm.php in core/modules/workspaces/src/Form/WorkspaceActivateForm.php
WorkspacePublishFormTest.php in core/modules/workspaces/tests/src/Kernel/WorkspacePublishFormTest.php
WorkspaceSwitcherForm.php in core/modules/workspaces/src/Form/WorkspaceSwitcherForm.php

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