Subclassing

To use a subclass of Document a database mapping has to be defined:

namespace Vendor\Extension\Domain\Model;

class MyClass extends \Cundd\DocumentStorage\Domain\Model\Document {}

config.tx_extbase.persistence.classes {
    Vendor\Extension\Domain\Model\MyClass {
        mapping {
            tableName = tx_documentstorage_domain_model_document
        }
    }
}