8 files declare their use of SolrCommitTrait in Search API Solr 4.x

FacetsTest.php in tests/src/Functional/FacetsTest.php

IntegrationTest.php in tests/src/Functional/IntegrationTest.php

IntegrationTest.php in modules/search_api_solr_defaults/tests/src/Functional/IntegrationTest.php

SearchApiSolrBackend.php in src/Plugin/search_api/backend/SearchApiSolrBackend.php

SearchApiSolrTest.php in tests/src/Kernel/SearchApiSolrTest.php

SolrBackendTestBase.php in tests/src/Kernel/SolrBackendTestBase.php

SolrBackendTrait.php in tests/src/Kernel/Processor/SolrBackendTrait.php

ViewsTest.php in tests/src/Functional/ViewsTest.php