toJson method
convert to json (all Metadata fields, only non-null/non-empty)
Implementation
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = {};
if (pubKey.isNotEmpty) data['pubKey'] = pubKey;
if (content.isNotEmpty) data['content'] = content;
if (tags.isNotEmpty) data['tags'] = tags;
if (refreshedTimestamp != null) {
data['refreshedTimestamp'] = refreshedTimestamp;
}
if (sources.isNotEmpty) data['sources'] = sources;
if (updatedAt != null) data['updatedAt'] = updatedAt;
return data;
}