toJson method
Implementation
Map<String, Object?> toJson() => <String, Object?>{
"version": formatVersion,
"updated": _updatedAt.toIso8601String(),
if (author.isNotEmpty) "author": author,
"markups": _markups.map((UDocMarkup markup) => markup.toJson()).toList(),
"bookmarks": _bookmarks.map((UDocBookmark bookmark) => bookmark.toJson()).toList(),
if (_shapes.isNotEmpty) "shapes": _shapes.map((UDocShape shape) => shape.toJson()).toList(),
};