I am not sure I understand what the use of auto_validate field is in stock.move. The only place I find it used is in stock.move.action_done()

        # Downstream move should only be triggered if this move is the last pending upstream move
        other_upstream_move_ids = self.search(cr, uid, [('id','!=',move.id),('state','not in',['done','cancel']),
                                    ('move_dest_id','=',move.move_dest_id.id)], context=context)
        if not other_upstream_move_ids:
            self.write(cr, uid, [move.id], {'move_history_ids': [(4, move.move_dest_id.id)]})
            if move.move_dest_id.state in ('waiting', 'confirmed'):
                self.force_assign(cr, uid, [move.move_dest_id.id], context=context)
                if move.move_dest_id.picking_id:
                    wf_service.trg_write(uid, 'stock.picking', move.move_dest_id.picking_id.id, cr)
                if move.move_dest_id.auto_validate:
                    self.action_done(cr, uid, [move.move_dest_id.id], context=context)

I'm fuzzy on what happens here. Does anybody know what the condition is that sets the auto_validate field to True?