protected function validateRelatedResourceExists($field, \CFX\JsonApi\ResourceInterface $r, $required = true)
    {
        if ($r !== null) {
            try {
                $r->initialize();
                $result = true;
            } catch (ResourceNotFoundException $e) {
                $result = false;
            }
        } else {
            $result = !$required;
        }

        if ($result) {
            $this->clearError($field, 'exists');
            return true;
        } else {
            $this->setError($field, 'exists', [
                "title" => "Invalid Relationship `$field`",
                "detail" => "The `$field` you've indicated for this order is not currently in our system."
            ]);
            return false;
        }
    }