Reader
Magento\Webapi\Model\Config\Reader
What it does
This class reads and parses Magento 2 Web API configuration files (webapi.xml) that define REST and SOAP API routes, resources, and parameters.
It extends the framework's filesystem config reader and specifies which XML attributes should be used as identifiers when merging multiple webapi.xml files from different modules.
Developers interact with this indirectly when defining API endpoints in their modules.