Domain model objects

Author.kt

class Author {
    var id: Int? = null

    var name: String? = null

    var surname: String? = null

    var birthDate: Date? = null

    val books: MutableList<Book> = ArrayList()

    // the default constructor is required by MapStruct to convert
    // a DTO object into a model domain object
    constructor()

    constructor(id : Int, name: String, surname: String, birthDate: Date) {
        this.id = id
        this.name = name
        this.surname = surname
        this.birthDate = birthDate
    }

    constructor(id: Int, name: String, surname: String, birthDate: Date, books: List<Book>) : this(id, name, surname, birthDate) {
        this.books.addAll(books)
    }
}

Book.kt

class Book {
    var id: Int? = null

    var title: String? = null

    var releaseDate: Date? = null

    // the default constructor is required by MapStruct to convert
    // a DTO object into a model domain object
    constructor()

    constructor(id : Int, title : String, releaseDate: Date) {
        this.id = id
        this.title = title
        this.releaseDate = releaseDate
    }
}