Find a Tender never sends tender.tenderPeriod.startDate, so an
opportunity's start date was always empty, and its end date was the
bid deadline. Start and end are now the contract period: from the
contracts' periods, else the awards' contract periods, else the lots'
contract periods, each date on its own, taking the earliest start and
the latest end of several.
The bid deadline (tenderPeriod.endDate) moves to a new closing_date
column (migration 00009), in the API as closing_date. EU Supply's
pages give no contract period, so its start and end are left empty
and its response deadline is the closing date.
bwilliams
50ee510520