7 files declare their use of SimpleSitemapPluginBase in Simple XML sitemap 4.x

CustomUrlGenerator.php in src/Plugin/simple_sitemap/UrlGenerator/CustomUrlGenerator.php

EntityMenuLinkContentUrlGenerator.php in src/Plugin/simple_sitemap/UrlGenerator/EntityMenuLinkContentUrlGenerator.php

EntityUrlGenerator.php in src/Plugin/simple_sitemap/UrlGenerator/EntityUrlGenerator.php

EntityUrlGeneratorBase.php in src/Plugin/simple_sitemap/UrlGenerator/EntityUrlGeneratorBase.php

SitemapGeneratorBase.php in src/Plugin/simple_sitemap/SitemapGenerator/SitemapGeneratorBase.php

UrlGeneratorBase.php in src/Plugin/simple_sitemap/UrlGenerator/UrlGeneratorBase.php

ViewsUrlGenerator.php in modules/simple_sitemap_views/src/Plugin/simple_sitemap/UrlGenerator/ViewsUrlGenerator.php