Create

//  Create a Map to store all the data of a Payment
List<Object> paymentsList = new List<Object>();
Map<String, Object> paymentMap = new Map<String, Object>();
    paymentMap.put('DateString', '2021-11-11T00:00:00');
    paymentMap.put('Amount', 50);
    paymentMap.put('Reference', 'Test Payment');

    //  Initializing the Invoice
    Map<String, Object> invoiceMap = new Map<String, Object>();
    invoiceMap.put('InvoiceID', '93151e60-3cad-4384-a2ed-99935444a218');
    paymentMap.put('Invoice', invoiceMap);

    Map<String, Object> accountMap = new Map<String, Object>();
    accountMap.put('Code', '880');
    paymentMap.put('Account', accountMap);

    paymentsList.add(paymentMap);
//  Initializing the RequestJSON Data to be passed.
    Map<String, Object> reqJSONMap = new Map<String, Object>(); 
    reqJSONMap.put('payments', paymentsList); 
    String reqJSON = JSON.serialize(reqJSONMap); 

    Map<String, Object> finalReqMap = new Map<String, Object>(); 
    Map<String, Object> reqOptions = new Map<String, Object>(); 
    finalReqMap.put('queryParameters', reqOptions); 
    finalReqMap.put('version', '1.0'); 
    finalReqMap.put('action', 'createPayment'); 
    finalReqMap.put('RequestJSON', reqJSON); 
    finalReqMap.put('skipDML', false); 
    //Required, if Xero Multi-Org is enabled in Breadwinner. 
    finalReqMap.put('xeroOrgId', '!aa00TM'); 
    System.debug('Request ::: ' + finalReqMap);

//  Placing a request to Breadwinner Global API
    Map<String, Object> respMap = bread_winner.BreadwinnerXeroAPI.call(finalReqMap);
    System.debug('Response ::: ' + respMap);