I found no Branch.java or persistent Branch entity in the current non-commercial server source.

Current representation and identity handling:

• Branches are native Git refs under refs/heads/. Project.getBranchRefs() obtains them from GitService, and RefFacade contains only the ref name plus the referenced/peeled Git objects.
• The repository REST API likewise exposes a branch as refName and tip commitHash; it does not expose an owner or creator.
• The branches page displays the tip commit author/committer via ContributorPanel. That is commit authorship, not branch ownership.
• A Git push creates a RefUpdated event carrying the authenticated OneDev user, so listeners can identify who performed that update. This is event context, not durable per-branch metadata. Server-side branch creation through GitService.createBranch(...) emits the event without a user.
• Branch authorization is evaluated from project permissions and branch protection rules for the acting user; it is not based on an owner field.
• Issue-to-branch association is also not persisted on a branch model. Issue.getBranch() scans refs and recognizes the issue-<number>[-<title>] naming convention.

I also found no branch-related isDraft, getDraft, setDraft, or equivalent draft field. Branch names are required and validated as Git ref names, so there is no unnamed-branch state. The few source occurrences of “unnamed” or “draft” are unrelated infrastructure/UI-library terminology.

So if branch ownership, draft branches, or unnamed placeholders are needed, they would be new persisted metadata rather than extensions to an existing branch model.