The HTML an email broadcast actually sent, one entry per distinct document.

A broadcast points at its template rather than copying it, so the template's body
(GET /api/v2/emails/templates/{id}?expand[]=html_body) shows the template as it is now and
changes if the template is edited after the send. This endpoint returns what recipients
received, as recorded when each send went out: the template plus the preview text,
mailing address and branding the workspace adds, before merge tags were filled in and links
were rewritten per contact. No contact data is included.

A split-test broadcast returns one version per variant whose preview text differs. Variants
that differ only in subject share a document, because the subject is not part of it. Match a
version to the broadcast's variants (GET /api/v2/emails/broadcasts/{id}) by
preheadline. A broadcast whose template or workspace settings changed while it was sending
returns a version for each document it sent.

Broadcasts that sent before documents were recorded (about mid-2023), and broadcasts that
have not sent, return an empty versions list.