data class OpdsMetadata(val title: String, val numberOfItems: Int? = null, val itemsPerPage: Int? = null, val currentPage: Int? = null, val modified: Instant? = null, val position: Int? = null, val rdfType: String? = null)
data class Builder(var title: String, var numberOfItems: Int? = null, var itemsPerPage: Int? = null, var currentPage: Int? = null, var modified: Instant? = null, var position: Int? = null, var rdfType: String? = null)