Time widget doesn't save hours not available in selection widget and not show 00:00:00
Since #4457 (closed) , Time widget is a selection with default half and hours:
00:00:00
00:30:00
...
1. When select 00:00:00 option, time widget is None (empty).
2- When write a new hour (not select an hour in selection widget), for example, 04:30:00, don't save it (show "saved record" alert). In this case, some times can't select because there aren't options in selector:
00:25:00
00:45:30
...
Tested at ir.cron next_call time widget.