toJson method
Implementation
Object toJson() => {
titles: titles,
creators: creators,
subjects: subjects,
description: description,
publishers: publishers,
contributors: contributors,
dates: dates,
types: types,
formats: formats,
identifiers: identifiers,
sources: sources,
languages: languages,
relations: relations,
coverages: coverages,
rights: rights,
metaItems: metaItems
};