- Native return types required by Symfony 7 (form types, commands, Twig
  extensions, subscribers, transformers, Doctrine types...): only the 311
  methods reported by the DebugClassLoader.
- Commands: #[AsCommand] instead of the static $defaultName (removed in
  Symfony 7).
- Migrations: App\Utils\ContainerAwareMigrationInterface instead of
  ContainerAwareInterface (removed in Symfony 7, all migrations are loaded
  by doctrine:migrations).
- Declared properties instead of dynamic ones (deprecated since PHP 8.2).
- Explicit nullable parameters (PHP 8.4), number_format(null), ${var}
  strings, optional parameters before required ones.
- ApiNormalizer: $context argument and getSupportedTypes().
- Kernel: .container.dumper.* parameters.