Function manifest_from 

pub fn manifest_from(
    version: Version,
    payload_schema: u32,
    provenance: Provenance,
    descriptor_sha256: Option<Sha256>,
    files: &BTreeMap<String, Vec<u8>>,
    metadata: &BTreeMap<String, Vec<u8>>,
) -> ReleaseManifest

Build a manifest from a set of logical paths and their bytes.

Shared by every bundle, so identity is computed one way whichever transport served the bytes.