private function getDueClauses()
    {
        $ex = new Expr();

        return $ex->orX(
            $ex->andX(
                $ex->eq('t.trigger', ':trigger_invoiced'),
                $ex->in('o.invoiceState', ':state_invoiced')
            ),
            $ex->andX(
                $ex->eq('t.trigger', ':trigger_fully_invoiced'),
                $ex->eq('o.invoiceState', ':state_fully_invoiced')
            ),
            $ex->andX(
                $ex->eq('t.trigger', ':trigger_shipped'),
                $ex->in('o.shipmentState', ':state_shipped')
            ),
            $ex->andX(
                $ex->eq('t.trigger', ':trigger_fully_shipped'),
                $ex->eq('o.shipmentState', ':state_fully_shipped')
            )
        );
    }
private function getDueClauses()
    {
        $ex = new Expr();

        return $ex->orX(
            $ex->andX(
                $ex->eq('t.trigger', ':trigger_invoiced'),
                $ex->in('o.invoiceState', ':state_invoiced')
            ),
            $ex->andX(
                $ex->eq('t.trigger', ':trigger_fully_invoiced'),
                $ex->eq('o.invoiceState', ':state_fully_invoiced')
            ),
            $ex->andX(
                $ex->eq('t.trigger', ':trigger_shipped'),
                $ex->in('o.shipmentState', ':state_shipped')
            ),
            $ex->andX(
                $ex->eq('t.trigger', ':trigger_fully_shipped'),
                $ex->eq('o.shipmentState', ':state_fully_shipped')
            )
        );
    }
Returns the due clause:
- payment term triggered
- payment date lower than or equal today

@return Expr\Base