Data
Magento\Indexer\Model\Config\Data
What it does
This class provides access to indexer configuration data loaded from XML files.
It extends Magento's base Config\Data class to add automatic cleanup of orphaned indexer states - when the configuration is refreshed, it removes any database records for indexers that no longer exist in the configuration.
Developers typically don't interact with this class directly, as it's used internally by the indexer system to manage configuration and state consistency.