6 files declare their use of SearchIndexingInterface

HelpSearch.php in core/modules/help/src/Plugin/Search/HelpSearch.php
HelpSearchPluginTest.php in core/modules/help/tests/src/Kernel/HelpSearchPluginTest.php
HelpSearchPluginTest.php in core/modules/search/modules/search_help/tests/src/Kernel/HelpSearchPluginTest.php
NodeSearch.php in core/modules/node/src/Plugin/Search/NodeSearch.php
SearchHelpSearch.php in core/modules/search/modules/search_help/src/Plugin/Search/SearchHelpSearch.php
SearchPage.php in core/modules/search/src/Entity/SearchPage.php

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