6 files declare their use of BusinessRulesVariablePlugin in Business Rules 8

CustomValueVariable.php in src/Plugin/BusinessRulesVariable/CustomValueVariable.php

EntityEmptyVariable.php in src/Plugin/BusinessRulesVariable/EntityEmptyVariable.php

EntityFieldVariable.php in src/Plugin/BusinessRulesVariable/EntityFieldVariable.php

UrlVariable.php in src/Plugin/BusinessRulesVariable/UrlVariable.php

UserVariable.php in src/Plugin/BusinessRulesVariable/UserVariable.php

ViewResultVariable.php in src/Plugin/BusinessRulesVariable/ViewResultVariable.php