Incompatible default value in UnitOfWork

[rmbl]

I get the following error when updating phpcr-odm in an older project.

Cannot assign null to property Symfony\Component\Routing\Route::$condition of type string

condition was only added in newer versions and is not available in the old node entries. I was able to "fix" it by checking if the field is nullable before setting the default value in doctrine/phpcr-odm/lib/Doctrine/ODM/PHPCR/UnitOfWork.php:532 but that feels a bit hacky.

Is there any way to easily migrate the old nodes to this newer version or is this a bug?