6 files declare their use of SchemaDurationBase in Schema.org Metatag 8

SchemaMetatagTestDuration.php in tests/modules/schema_metatag_test/src/Plugin/metatag/Tag/SchemaMetatagTestDuration.php

SchemaMovieDuration.php in schema_movie/src/Plugin/metatag/Tag/SchemaMovieDuration.php

SchemaRecipeCookTime.php in schema_recipe/src/Plugin/metatag/Tag/SchemaRecipeCookTime.php

SchemaRecipePrepTime.php in schema_recipe/src/Plugin/metatag/Tag/SchemaRecipePrepTime.php

SchemaRecipeTotalTime.php in schema_recipe/src/Plugin/metatag/Tag/SchemaRecipeTotalTime.php

SchemaVideoObjectDuration.php in schema_video_object/src/Plugin/metatag/Tag/SchemaVideoObjectDuration.php