toJson method
Implementation
core.Map<core.String, core.dynamic> toJson() => {
if (bookDisplayNumber != null) 'bookDisplayNumber': bookDisplayNumber!,
if (kind != null) 'kind': kind!,
if (shortSeriesBookTitle != null)
'shortSeriesBookTitle': shortSeriesBookTitle!,
if (volumeSeries != null) 'volumeSeries': volumeSeries!,
};