Payment number (L<FS::cust_pay>) of the completed payment.
+=item void_paynum
+
+Payment number of the payment if it's been voided.
+
=item invnum
Invoice number (L<FS::cust_bill>) to try to apply this payment to.
|| $self->ut_foreign_keyn('paynum', 'cust_pay', 'paynum' )
|| $self->ut_foreign_keyn('pkgnum', 'cust_pkg', 'pkgnum')
|| $self->ut_foreign_keyn('invnum', 'cust_bill', 'invnum')
+ || $self->ut_foreign_keyn('void_paynum', 'cust_pay_void', 'paynum' )
|| $self->ut_flag('manual')
|| $self->ut_numbern('discount_term')
|| $self->payinfo_check() #payby/payinfo/paymask/paydate