symfony/symfony — comment on commit b8d8cab1f98a8b3491be57109f9de1ee5a802363
File: src/Symfony/Component/Form/Extension/Validator/Type/FieldTypeValidatorExtension.php line 50
By bschussek:

You can override the validator extension with a custom one. Create an extension of the class where you override getDefaultOptions() and register it in the DIC using the same tag as the class bundled in the core. Then it should be used instead AFAIK.