question: public String paymentTerm ( Properties ctx , int WindowNo , GridTab mTab , GridField mField , Object value ) { Integer C_PaymentTerm_ID = ( Integer ) value ; int C_Invoice_ID = Env . getContextAsInt ( ctx , WindowNo , "C_Invoice_ID" ) ; if ( C_PaymentTerm_ID == null || C_PaymentTerm_ID . intValue ( ) == 0 || C_Invoice_ID == 0 ) return "" ; MPaymentTerm pt = new MPaymentTerm ( ctx , C_PaymentTerm_ID . intValue ( ) , null ) ; if ( pt . get_ID ( ) == 0 ) return "PaymentTerm not found" ; boolean valid = pt . apply ( C_Invoice_ID ) ; mTab . setValue ( "IsPayScheduleValid" , valid ? "Y" : "N" ) ; return "" ; }
target:  Set Payment Term. Payment Term has changed 