src/Payum/Core/Storage/FilesystemStorage.php
protected function doGetIdentity($model)
    {
        $rp = new \ReflectionProperty($model, $this->idProperty);
        $rp->setAccessible(true);

        if (false == $id = $rp->getValue($model)) {
            throw new LogicException('The model must be persisted before usage of this method');
        }

        return new Identity($id, $model);
    }
protected function doGetIdentity($model)
    {
        $rp = new \ReflectionProperty($model, $this->idProperty);
        $rp->setAccessible(true);

        if (false == $id = $rp->getValue($model)) {
            throw new LogicException('The model must be persisted before usage of this method');
        }

        return new Identity($id, $model);
    }
{@inheritDoc}