/// Index into `Document::assets`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]pubstructAssetId(pub usize);/// An embedded binary asset (image, object payload). Bytes are always
/// retained so the document stays self-contained; total retained bytes are
/// capped by the fixed `max_asset_total_bytes` limit at parse time.
#[derive(Debug, Clone)]pubstructAsset{/// This asset's own index, so a detached `Asset` still identifies itself.
pubid: AssetId,
/// MIME type, e.g. `image/png`.
pubmedia_type: String,
/// Package part or stream the asset came from, for provenance.
puborigin_part: String,
/// The payload, exactly as stored in the source.
pubbytes:Vec<u8>,
}