// create list of sale items
List<SaleItem> items = new ArrayList<>(1);
items.add(new SaleItem(SaleItemType.PURCHASE, "item 1", new BigDecimal("10"), null, new BigDecimal("1"), new BigDecimal("20"), new BigDecimal("10"), null, null, null));

// you can put requested objects or use more convenient way via builder which can lead you through mandatory fields
accept.sales()
        .pay(SaleBuilder.newBuilder()                       // builder will guide you what you have to put
                .setAmount(new BigDecimal("10"))            // amount of whole sale, mandatory field
                .setCurrency(Currency.getInstance("EUR"))   // currency of whole sale, mandatory field
                .unitPricesIncludeTax()                     // choose if tax is included or excluded, mandatory field but you can choose from 3methods, unitPricesIncludeTax(), unitPricesExcludeTax(), setUnitPricesIncludeTax(boolean unitPricesIncludeTax)
                .addAlipayPayment(new BigDecimal("10"), "scannedConsumerIdFromAlipayApplication")
                //or
                .addWechatPayment(new BigDecimal("10"), "scannedConsumerIdFromWechatApplication")
                .setSaleItems(items)
                .setCashierId("cashier id")
                // ...
                .build()
        )
        .subscribeParallel(eventRelay)
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(saleId -> {
          // sale was performed successfully
          // saleId String is returned, you can load whole sale object by calling accept.sales().getSale(String saleId)
        }, throwable -> {
          // handle error
        });
eventRelay
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(event -> {
            if (event instanceof Event.Update) {             // update events indicates change of progress
                String update = ((Event.Update) event).getMessage(context);
            }
            else if (event instanceof Event.PasswordConfirmation) {   //wechat payment method can ask for confirmation, that customer entered pin
                onPasswordConfirmation((Event.PasswordConfirmation) event);
            }
         });