In Magento Product class (MagentoCatalogModelProduct)
there is the function
public function setExtensionAttributes(MagentoCatalogApiDataProductExtensionInterface $extensionAttributes)
However, if I look at Magento codebase (e.g. https://github.com/magento/magento2/tree/2.4-develop/app/code/Magento/Catalog/Api/Data) there is no MagentoCatalogApiDataProductExtensionInterface.
How come? There is probably something that I have not understood fully, please enlighten me.