/// <summary> /// Initializes a new instance of the <see cref="Header"/> class. /// </summary> /// <param name="headerItem">The item from this header.</param> /// <exception cref="ArgumentNullException"> /// <paramref name="headerItem"/> is <see langword="null"/>. /// </exception> public Header(HeaderItem headerItem) { if (headerItem == null) { throw new ArgumentNullException(nameof(headerItem), "The header item cannot be null."); } Items = ListUtility.CreateSingleElementList(headerItem).AsReadOnly(); }