TimelineItem

By kind, with its own fields: comment (comment), labeled and unlabeled (label, as it was then), assigned and unassigned (assignee), renamed (from, to), project_changed (from, from_path, to, to_path), linked (repo, repo_path, branch, source, sha), unlinked (repo, repo_path, branch, source), closed (reason, merge: the merge that closed it, or null), reopened, merge_referenced (merge: a merge that named it after it was closed).