toJson method
Implementation
core.Map<core.String, core.dynamic> toJson() => {
if (customVoice != null) 'customVoice': customVoice!,
if (languageCode != null) 'languageCode': languageCode!,
if (name != null) 'name': name!,
if (ssmlGender != null) 'ssmlGender': ssmlGender!,
};