public function toArray()
    {
        return [
            'field' => $this->column,
            'references' => $this->references,
            'on' => $this->on,
            'on-delete' => $this->onDelete,
            'on-update' => $this->onUpdate,
            'references-model' => $this->getReferencesModel(),
            'is-self-reference' => $this->isSelfReference(),
        ];
    }