6 files declare their use of Runtime in Acquia Search 3.x

AcquiaSearchCommands.php in src/Commands/AcquiaSearchCommands.php

acquia_search.install in ./acquia_search.install

Install, update, and uninstall functions for the Acquia Search Solr module.

acquia_search.module in ./acquia_search.module

Integration between Drupal and Acquia's hosted Solr search service.

RuntimeTest.php in tests/src/Unit/Helper/RuntimeTest.php

SearchApiSolrAcquiaConnector.php in src/Plugin/SolrConnector/SearchApiSolrAcquiaConnector.php

SearchSubscriber.php in src/EventSubscriber/SearchSubscriber.php