Source.fromMap constructor Null safety
Implementation
Source.fromMap(Map<String, dynamic> map){
accountNumber = map['AccountNumber'] ?? '';
amount = (map['Amount'] ?? 0).toDouble();
transactionCurrency = map['TransactionCurrency'] ?? '';
narration = map['Narration'] ?? '';
responseCode = map['ResponseCode'] ?? '';
responseDescription = map['ResponseDescription'] ?? '';
}