copy method
Implementation
Metadata copy() {
return Metadata(
modificationTime: modificationTime,
applicationVersion: applicationVersion,
tagsGroups: List<dynamic>.from(tagsGroups),
quickAccess: List<dynamic>.from(quickAccess),
smartFolders: List<dynamic>.from(smartFolders),
folders: folders.map((folder) => folder.copy()).toList(),
);
}