6 files declare their use of FlagMapping in Flags 8

ConfigEntityFormBase.php in flags_ui/src/Form/ConfigEntityFormBase.php

CountryMappingEditForm.php in flags_ui/src/Form/CountryMappingEditForm.php

CountryMappingForm.php in flags_ui/src/Form/CountryMappingForm.php

LanguageConfigEntityFormBase.php in flags_ui/src/Form/LanguageConfigEntityFormBase.php

LanguageFlagMappingListBuilder.php in src/Entity/LanguageFlagMappingListBuilder.php

LanguageMappingEditForm.php in flags_ui/src/Form/LanguageMappingEditForm.php