Adding new enum values in the extension metadata will not break compatibility after this change, it will now use the default if an invalid value is found.
Currently, in code.quarkus.io all the resteasy-reactive extensions have the `code` tag. This is because we needed a way to avoid having the classic resteasy starter code with those extensions. As a workaround we used the `core` kind which isn't showing the `code` tag but still referencing the codestart. In a few versions we will be able to introduce `default-codestart` without much risk.