9 files declare their use of ConfigurablePropertyInterface in Search API 8

AggregatedFieldProperty.php in src/Plugin/search_api/processor/Property/AggregatedFieldProperty.php

Field.php in src/Item/Field.php

FieldConfigurationForm.php in src/Form/FieldConfigurationForm.php

FieldsHelper.php in src/Utility/FieldsHelper.php

IndexAddFieldsForm.php in src/Form/IndexAddFieldsForm.php

IndexFieldsForm.php in src/Form/IndexFieldsForm.php

SearchApiFieldTrait.php in src/Plugin/views/field/SearchApiFieldTrait.php

SearchApiQuery.php in src/Plugin/views/query/SearchApiQuery.php

ViewsPropertyExtractionTest.php in tests/src/Kernel/Views/ViewsPropertyExtractionTest.php