9 files declare their use of ServiceDefinitionBase in Services 8.4

AliasGet.php in src/Plugin/ServiceDefinition/AliasGet.php

EntityDelete.php in src/Plugin/ServiceDefinition/EntityDelete.php

EntityGet.php in src/Plugin/ServiceDefinition/EntityGet.php

EntityIndex.php in src/Plugin/ServiceDefinition/EntityIndex.php

EntityView.php in src/Plugin/ServiceDefinition/EntityView.php

TestServiceDefinition.php in services_test/Plugin/ServiceDefinition/TestServiceDefinition.php

UserLogin.php in src/Plugin/ServiceDefinition/UserLogin.php

UserLogout.php in src/Plugin/ServiceDefinition/UserLogout.php

VocabularyTreeGet.php in src/Plugin/ServiceDefinition/VocabularyTreeGet.php