All classes that implement ConfigurationExtensionInterface

class \Symfony\Component\HttpKernel\DependencyInjection\ConfigurableExtension
class \Symfony\Component\HttpKernel\DependencyInjection\Extension implements ConfigurationExtensionInterface, ExtensionInterface
class \Symfony\Component\HttpKernel\Tests\Fixtures\ExtensionLoadedBundle\DependencyInjection\ExtensionLoadedExtension
class \Symfony\Component\HttpKernel\Tests\Fixtures\ExtensionPresentBundle\DependencyInjection\ExtensionPresentExtension