toJson method
Implementation
core.Map<core.String, core.dynamic> toJson() => {
if (cost != null) 'cost': cost!,
if (currencyCode != null) 'currencyCode': currencyCode!,
if (id != null) 'id': id!,
if (revenue != null) 'revenue': revenue!,
if (tax != null) 'tax': tax!,
};