Reader
Magento\PageBuilder\Model\Config\ContentType\Reader
What it does
This class reads and parses XML configuration files that define Page Builder content types from the content_type directory.
It extends Magento's filesystem config reader to handle the specific structure of Page Builder content type definitions, including appearances, breakpoints, elements, and converters.
Developers use this when the system needs to load and merge all content type configurations during Page Builder initialization.