toJson method
Implementation
Map<String, dynamic> toJson() => {
'id': id,
'name': name,
if (description != null) 'description': description,
if (category != null) 'category': category,
if (gender != null) 'gender': gender,
if (accent != null) 'accent': accent,
if (previewUrl != null) 'preview_url': previewUrl,
};