6 files declare their use of EntityProcessorBase in Content Synchronizer 8

EntityPublisher.php in src/Service/EntityPublisher.php

FileProcessor.php in src/Plugin/content_synchronizer/entity_processor/FileProcessor.php

NodeProcessor.php in src/Plugin/content_synchronizer/entity_processor/NodeProcessor.php

ParagraphProcessor.php in src/Plugin/content_synchronizer/entity_processor/ParagraphProcessor.php

TaxonomyTermProcessor.php in src/Plugin/content_synchronizer/entity_processor/TaxonomyTermProcessor.php

UserProcessor.php in src/Plugin/content_synchronizer/entity_processor/UserProcessor.php