toJson method
Implementation
core.Map<core.String, core.dynamic> toJson() => {
if (author != null) 'author': author!,
if (canonicalVolumeLink != null)
'canonicalVolumeLink': canonicalVolumeLink!,
if (coverUrl != null) 'coverUrl': coverUrl!,
if (description != null) 'description': description!,
if (title != null) 'title': title!,
if (volumeId != null) 'volumeId': volumeId!,
};