public function attachmentsMetadata()
    {
        if ($this->attachmentsMetadata === null) {
            $this->attachmentsMetadata = [];

            $metadata = $this->metadata();
            if (isset($metadata['attachments'])) {
                $this->attachmentsMetadata = $this->mergePresets($metadata['attachments']);
            }
        }

        return $this->attachmentsMetadata;
    }