adata.\nThe form contains:\n- Blobs identified by their identifiers as field names\n- An optional `_metadata` field containing a JSON array with per blob Walrus-native metadata\n\n# Contents of Walrus-native metadata\n- `identifier`: The identifier of the blob, must match the corresponding blob field name\n- `tags`: JSON object with string key-value pairs (optional)\n\nBlobs without corresponding metadata entries will be stored with empty tags.\n\n# Examples\n\n## Blobs without Walrus-native metadata, with 