AbstractMapper
Magento\Config\Model\Config\Structure\AbstractMapper
What it does
This abstract class serves as a base for mapper classes that transform system configuration data structures in Magento 2.
Developers extend this class when creating custom mappers to convert configuration arrays, utilizing the protected helper method to safely check for nested values using slash-separated paths.
It's part of Magento's system configuration infrastructure used during the processing of system.xml files.