def _migrate_contribution_timetable_entry(self, old_entry, session_block=None):
        old_contrib = old_entry._LinkedTimeSchEntry__owner
        contrib = self.legacy_contribution_map[old_contrib]
        contrib.timetable_entry = TimetableEntry(event_new=self.event, start_dt=old_contrib.startDate)
        self._migrate_location(old_contrib, contrib)
        if session_block:
            contrib.session = session_block.session
            contrib.session_block = session_block
            contrib.timetable_entry.parent = session_block.timetable_entry
        return contrib.timetable_entry