6 files declare their use of ProcessorProperty in Search API 8

AggregatedFieldsTest.php in tests/src/Unit/Processor/AggregatedFieldsTest.php

ContentAccess.php in src/Plugin/search_api/processor/ContentAccess.php

HighlightTest.php in tests/src/Unit/Processor/HighlightTest.php

LanguageWithFallback.php in src/Plugin/search_api/processor/LanguageWithFallback.php

RoleAccess.php in src/Plugin/search_api/processor/RoleAccess.php

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