public function saveDocumentType($slug, $postValues)
    {
        $documentTypeObject = DocumentTypeFactory::createDocumentTypeFromPostValues($postValues);

        $documentTypes = $this->repository->documentTypes;
        foreach ($documentTypes as $key => $documentType) {
            if ($documentType->slug == $slug) {
                $documentTypes[$key] = $documentTypeObject;
            }
        }
        $this->repository->documentTypes = $documentTypes;
        $this->save();
    }