I'm creating a custom product type. I want to have the option of adding configurations (red shirt, green shirt,...). The problem is that there is something in Magento_ConfigurableProduct that the moment you add a configuration it changes the product type to 'configurable'. I cannot change the product type in my type class because once you add configurations I doesn't use this class anymore. Does someone now where it changes the product type (class / file & function)?
ps. I'm not using my custom product types for shirts this is just an example.