toJson method
Implementation
@override
Map<String, dynamic> toJson() => {
'type': integer ? 'integer' : 'number',
if (title != null) 'title': title,
if (description != null) 'description': description,
if (defaultValue != null) 'default': defaultValue,
if (minimum != null) 'minimum': minimum,
if (maximum != null) 'maximum': maximum,
};